Condition Analysis
AI-powered assessment using site data and 14-day weather history
The rock is wet today following 6.1mm of rain and will remain so, with heavy rain forecast through the next four days totalling nearly 90mm. Despite rhyolite's non-porous nature, the sustained saturation and near-100% humidity mean surfaces will not dry out meaningfully this week.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The south-facing aspect would normally aid drying, but persistent cloud cover (near 100%) and high humidity negate any solar benefit this week.
- The 15–20 minute uphill approach means the boulders sit above the valley floor where cloud and mist often linger, keeping surfaces damp even between showers.
- Rhyolite at Wavelength has distinctive stratified formations with horizontal ledges and cracks that hold surface water and seepage longer than smooth faces.
- The Llanberis Pass funnels prevailing SW winds, but at 300m altitude the boulders may sit in cloud during prolonged wet spells like this one.
Warnings
2
- Rhyolite becomes extremely slippery when wet — friction-dependent problems at Wavelength pose a serious fall risk in current conditions.
- Heavy rain forecast June 18–20 (up to 28mm/day) may cause flash flooding and make the steep hillside approach treacherous.
Reasoning
The rock is currently wet from today's rain (6.1mm, with heavier falls from late afternoon) on top of a very wet preceding fortnight (118.6mm in 28 days), and humidity is at 94–100%.
With no consecutive dry days, persistent cloud cover, humidity above 85%, and only brief dry windows between showers, surface moisture has had no opportunity to evaporate.
Rhyolite is non-porous so there is no structural weakening concern, but the friction-dependent climbing at Wavelength becomes dangerously slippery when wet.
Early June in Snowdonia is prone to Atlantic frontal systems; the current pattern shows an extended wet spell with no significant dry window until at least June 22.
Contributing Factors
6
Over 85mm has fallen in the last two weeks with 6.1mm today alone, keeping all surfaces thoroughly wet.
Nearly 90mm is forecast over the next five days (June 17–21), ensuring the rock will remain saturated.
Humidity has averaged 83% over the past week and is forecast at 86–98% for the coming days, preventing any meaningful surface drying.
There have been no fully dry days recently, so the rock has had no drying window at all.
The south-facing aspect and partial wind exposure would normally aid drying, but persistent cloud and rain completely override these benefits.
Rhyolite does not absorb water, so once a genuine dry window arrives the surface will dry within hours rather than days.
Recommendations
3
- Do not visit Wavelength Boulders this week; conditions are wet and will worsen significantly through to June 21.
- Monitor the forecast for June 22 onward — if the predicted dry day materialises with wind and sun, surfaces could come into condition quickly.
- If in the area, consider indoor climbing at Beacon or The Indy Wall rather than risking slippery rhyolite.
Previous Analyses
Marginal — Assess Conditions
55%
2 days ago
After heavy rain on June 11 (21.5mm), the site has had three full dry days (June 12–14) with decent westerly winds, and today is mostly dry with warming temperatures through the afternoon. The south-facing rhyolite should have surface-dried, but the prolonged wet spell (112mm over 28 days) means seepage and residual dampness in sheltered spots are likely — climbers should visually check holds before committing.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The 15–20 minute uphill approach means the boulders sit at ~300m where cloud and mist can linger even when the valley floor is clear, potentially re-wetting surfaces overnight.
- South-facing aspect receives excellent solar radiation through the afternoon, which is the primary drying mechanism — the window from 10:00–17:00 today offers the best friction conditions.
- The stratified rhyolite formations can channel seepage along horizontal bedding planes after prolonged wet spells, so even apparently dry faces may have damp bands.
- The extended wet period (over 80mm in the last two weeks alone) means the ground and surrounding vegetation will be saturated, increasing ambient humidity at the boulders.
Warnings
2
- A prolonged wet spell begins tomorrow (72mm forecast over 5 days) — today's afternoon is likely the last climbing window for at least a week.
- Rising humidity from 18:00 onward (80%+) will rapidly degrade friction; plan to be off the boulders before evening.
Reasoning
The last significant rain was 21.5mm on June 11, followed by three dry days with moderate-to-strong westerly winds (25–32 km/h), which should have cleared surface moisture from the non-porous rhyolite, though sheltered faces and seepage lines may still be damp.
Three consecutive dry days with south/west aspect solar exposure and winds of 19–32 km/h provide reasonable drying conditions for non-porous rock, but today's 0.3mm precipitation and 72% humidity suggest the atmosphere is not aggressively dry.
Rhyolite is non-porous and does not suffer structural weakening when wet — the risk is purely friction-related on damp surfaces.
Early June in Snowdonia is within peak season but 2026 has delivered an unusually wet fortnight; long daylight hours and reasonable temperatures (13–20°C today) favour afternoon drying windows.
Contributing Factors
6
June 12–14 were completely dry with moderate winds, allowing non-porous rhyolite surfaces to shed the 21.5mm from June 11.
Over 80mm fell in the preceding two weeks with high humidity (81% average), saturating surrounding ground and increasing seepage risk.
The south aspect maximises solar radiation during long June days, accelerating surface evaporation especially between 10:00–17:00.
Hourly forecasts show dry conditions from 09:00–17:00 with humidity dropping to ~60% and temperatures reaching 20°C, ideal for friction.
Humidity remains elevated (72% daily average, rising to 90%+ by evening), limiting how completely surfaces can dry and risking condensation.
15.9mm forecast for June 16 followed by further heavy rain all week (72mm total), meaning today is the only viable window before an extended wet spell.
Recommendations
3
- Target the afternoon window between 10:00 and 17:00 today when humidity is lowest and solar heating is strongest — physically touch holds before committing to problems.
- Avoid shaded faces, horizontal seepage bands, and lower sections near saturated ground where residual dampness is most likely to persist.
- Bring a towel and brush to dry any damp patches on landings, and be prepared to walk away from problems that feel greasy — the upcoming week offers no dry alternatives.
Marginal — Assess Conditions
65%
3 days ago
After three consecutive dry days following a very wet period (50.5mm in the last week), the south-facing rhyolite should have surface-dried on exposed faces, but seepage and sheltered areas may still be damp. Conditions are promising for today but a prolonged wet spell returns from June 16th onwards.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The 15–20 minute uphill approach means conditions at the boulders may differ from what you see at road level — the higher altitude (300m) can hold cloud and moisture longer.
- Stratified rhyolite formations can channel seepage along bedding planes, so even after dry days, water may weep from horizontal cracks and overlaps on some problems.
- The south aspect and partial wind exposure are working well in the current northerly/calm conditions, maximising solar drying on the main faces.
- The recent extended wet spell (over 100mm in 28 days) means the hillside is saturated, increasing the chance of ground seepage affecting lower sections of boulders.
Warnings
2
- The hillside is heavily saturated from prolonged rain — watch for slippery ground on the steep approach, especially on the descent.
- Do not assume all problems are dry; the stratified rock can hold hidden seepage that emerges unexpectedly on certain lines.
Reasoning
Three full dry days with moderate wind and improving temperatures should have cleared surface moisture from exposed south-facing rhyolite, but the preceding extremely wet period (21.5mm on June 11, plus heavy rain on June 8 and earlier) means seepage lines and sheltered faces could still be damp.
South aspect with partial wind exposure at 300m, combined with today's northerly breeze and 15.8°C max, provides reasonable but not exceptional drying — the 78% humidity limits evaporation rate somewhat.
Rhyolite is non-porous and does not suffer structural weakening when wet; no hold breakage risk from moisture.
Early June in Snowdonia brings long daylight hours aiding drying, but this has been an unusually wet spell; the forecast shows another front arriving June 16–19, so today and tomorrow represent the best window.
Contributing Factors
6
No measurable rain since June 12, giving 2.5+ full days of drying on non-porous rhyolite.
Over 50mm fell in the preceding 7 days including 21.5mm on June 11, saturating the hillside and increasing seepage risk.
South-facing rock at midsummer receives strong solar radiation, accelerating surface evaporation significantly.
Average humidity around 78–82% over recent days slows evaporation and can leave a residual film on textured rock.
Heavy rain forecast from June 16–19 (over 30mm total) will reset drying conditions entirely.
Partial wind exposure with today's 15.5 km/h breeze aids surface drying across open faces.
Recommendations
3
- Visit today or tomorrow (June 15) for the best window — exposed south-facing problems should be dry, but check each boulder individually before committing.
- Avoid problems with obvious seepage lines, horizontal overlaps, or north-facing aspects where moisture may linger from the recent heavy rain.
- Bring a towel and soft brush; some surfaces may have a thin moisture film that needs checking, especially in the morning before sun hits the rock.
Marginal — Assess Conditions
60%
4 days ago
After a very wet period (nearly 59mm in the last 7 days), there have been two dry days with moderate westerly winds, which should have cleared surface moisture from this south-facing rhyolite. However, given the saturated ground conditions and high humidity, seepage and residual dampness in sheltered areas remain a real possibility — a visual check on arrival is essential.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The 15–20 minute uphill approach means conditions at the boulders may differ from what's visible at road level — the Pass floor can appear drier than the hillside above.
- The stratified formations and layered rhyolite can channel seepage water along horizontal bands, creating persistent damp patches even after the main surfaces have dried.
- The south-facing aspect is a significant advantage for drying, especially in mid-June with long daylight hours and good solar angles.
- High recent rainfall totals (59mm in 7 days) will have saturated the hillside above, and groundwater seepage through cracks and overlaps may persist for days regardless of surface drying.
Warnings
2
- Rhyolite becomes very slippery when wet — even a thin moisture film can cause unexpected foot slips on what appears to be dry rock.
- The hillside above the boulders is saturated; be alert for seepage appearing mid-session as groundwater migrates through cracks.
Reasoning
Two full dry days with moderate wind following 21.5mm on June 11 should have cleared most surface moisture from non-porous rhyolite, but the prolonged wet spell (nearly 60mm in 7 days) means seepage lines and sheltered faces may still be damp.
The south aspect and moderate westerly winds (23–32 km/h) over the last two days provide good drying conditions, and rhyolite's non-porous nature means surface water evaporates relatively quickly — likely dry on exposed faces but seepage-fed areas will lag.
Rhyolite is non-porous and does not suffer structural weakening when wet; no hold breakage risk from moisture.
Mid-June provides long daylight hours and reasonable solar radiation, which is favourable for drying, though the recent spell of cool, wet weather (avg 11.6°C, 84% humidity) has slowed evaporation compared to typical summer conditions.
Contributing Factors
6
Nearly 59mm fell in the last 7 days including 21.5mm on June 11, saturating the hillside and increasing seepage risk.
No meaningful rain on June 12–13, with moderate winds helping surface moisture evaporate from the non-porous rhyolite.
The southerly aspect receives strong solar radiation in mid-June, significantly accelerating surface drying.
Average humidity of 84% over the last week slows evaporation and may leave a film of moisture on shaded surfaces.
Westerly winds of 24–32 km/h over the last two days aid surface drying across exposed boulder faces.
Heavy rain is forecast from June 16 (18mm) through June 17 (43mm), closing the dry window quickly.
Recommendations
3
- Visit tomorrow (June 14) or June 15 for the best window — exposed south-facing problems should be dry, but check for seepage on overhangs and along stratified bands before committing.
- Carry a towel and brush to deal with residual damp patches, and be prepared to walk away from problems that show any sign of moisture.
- Avoid climbing from June 16 onwards as heavy rain (60mm+ forecast over three days) will reset conditions entirely.
Do Not Climb
35%
5 days ago
Despite today being dry, 21.5mm of rain fell just yesterday (June 11) following a prolonged wet spell totalling 62.7mm over the past week. With only one dry day, high humidity (83%), and moderate temperatures, the rock surfaces are very likely still damp, particularly in shaded or sheltered areas among the boulders.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The 15–20 minute uphill approach means the boulders sit at ~300m where cloud and mist can linger, keeping surfaces damp even on nominally dry days.
- The stratified formations at Wavelength create ledges and horizontal breaks that trap and channel water; seepage from these features can persist for 24–48 hours after heavy rain.
- The south-facing aspect is helpful for solar drying, but the recent spell of cool, overcast, high-humidity weather has limited effective solar radiation.
- The boulders are above the Climbers' Club hut on a hillside — good drainage helps runoff, but the sheer volume of recent rain (63mm in 7 days) means ground saturation can feed seepage onto lower boulder faces.
Warnings
2
- Rhyolite friction drops dramatically when damp — falls from apparently dry-looking but subtly moist holds are a real risk, especially on slabs and friction-dependent problems.
- The prolonged wet spell means the hillside above the boulders is saturated; delayed seepage onto boulder faces is likely even on dry days.
Reasoning
With 21.5mm falling yesterday and 62.7mm over the past week, rock surfaces are almost certainly still wet or damp despite today's dry spell, especially given 83% humidity and only moderate wind.
One dry day with westerly winds at 31 km/h and a south aspect provides some drying, but at 300m altitude with 83% humidity and only ~17°C, evaporation rates are insufficient to fully dry surfaces after such heavy recent rainfall.
Rhyolite is non-porous so there is no risk of structural weakening or hold breakage from moisture; the concern is purely friction loss on wet surfaces.
Early June in Snowdonia is typically changeable; the current wet pattern with below-average temperatures and high humidity is not unusual but limits drying windows significantly.
Contributing Factors
6
21.5mm fell yesterday and 62.7mm over the past 7 days, saturating the ground and boulder surfaces.
A single dry day is insufficient to fully dry stratified rhyolite surfaces after prolonged heavy rain, especially at this humidity.
Humidity at 83% today and averaging 85% over the past week significantly slows surface evaporation.
The south-facing aspect and 31 km/h westerly wind today provide the best available drying conditions, though not enough to overcome the moisture deficit.
Rhyolite does not absorb water, so only surface moisture and seepage need to dry — no structural damage risk.
At 300m, temperatures are a few degrees cooler than valley level, reducing evaporation efficiency.
Recommendations
3
- Wait at least one more full dry day before visiting; if June 13 stays dry as forecast, conditions on June 14 could be worth assessing in person.
- If you do visit, focus on the most exposed south-facing faces that catch direct sun and wind — avoid any recessed or north-facing surfaces.
- Bring a towel and soft brush, and be prepared to walk away if seepage is visible along the stratified ledges.
Do Not Climb
95%
6 days ago
The rock is thoroughly soaked after 67mm of rain in the last 7 days, including 25mm today with persistent heavy showers through the afternoon. With humidity near saturation and no meaningful dry window, conditions are clearly unsuitable for climbing today.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Wavelength Boulders sit at 300m on the south side of the Llanberis Pass, and while the south aspect aids drying in sunshine, the current prolonged wet spell with 100% cloud cover negates this advantage.
- The 15–20 minute uphill approach means the boulders are somewhat exposed to wind-driven rain from the prevailing SW, and the stratified rhyolite formations can hold surface water in horizontal seams and cracks.
- Seepage from the saturated hillside above can keep some boulder bases and lower faces wet long after rain stops, particularly after extended wet periods like the current one.
- The Llanberis Pass funnels moist south-westerly airflow, and at 300m altitude the site can sit in low cloud or mist for extended periods, keeping humidity at saturation and preventing drying.
Warnings
2
- Rhyolite becomes extremely slippery when wet — friction-dependent slab and face problems are dangerous in these conditions.
- The prolonged wet spell may cause hillside seepage that keeps some boulders wet even after surface rain dries.
Reasoning
The rock is saturated on the surface after 25mm of rain today on top of 67mm over the past week, with humidity at 94–100% and continuous rainfall through the day.
Despite partial wind exposure and south aspect, zero drying has occurred — there has been no dry window, 100% cloud cover all day, and near-saturation humidity prevents evaporation.
Rhyolite is non-porous and does not suffer structural weakening when wet, so hold breakage is not a concern.
Early June should offer improving conditions, but this is an unusually prolonged wet spell; long daylight hours will eventually aid rapid drying once rain stops and sun breaks through.
Contributing Factors
6
25mm of rain forecast today with the heaviest falls between 09:00 and 15:00, leaving every surface thoroughly wet.
67mm in the last 7 days across multiple rain events means the ground and rock have had no opportunity to dry out.
Humidity has been 83–100% all week and remains at 94–100% today, preventing any meaningful surface evaporation.
Complete cloud cover all day eliminates solar radiation that would normally help the south-facing rock dry.
Wind at 20–30 km/h provides some airflow but cannot dry rock that is being continuously rained on and surrounded by saturated air.
Rhyolite does not absorb water, so once rain stops and conditions improve, surface drying can be relatively quick.
Recommendations
3
- Do not visit today — the rock is thoroughly wet and dangerously slippery.
- Monitor the forecast for June 14th, which shows the first genuinely dry day with warmer temperatures and low wind; this could offer a window if the rock has time to dry.
- If visiting later this week, check the boulders in person — look for dry patches on overhanging faces first and test friction carefully before committing to any problems.
Do Not Climb
90%
8 days ago
Wavelength Boulders are currently wet and unsuitable for climbing. Heavy, persistent rainfall over the past week (64.5mm in 7 days) with no consecutive dry days, combined with further rain today and in the forecast, means surfaces will be saturated and dangerously slippery despite rhyolite's non-porous nature.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The 15–20 minute uphill approach means the boulders sit at ~300m where cloud base and hill fog are common in prolonged wet spells, further slowing any drying.
- The south-facing aspect is helpful for drying in sunny conditions, but recent and forecast cloud cover (mostly 80–100%) severely limits solar input.
- Stratified rhyolite formations can channel and hold surface water in horizontal breaks and seepage lines longer than smooth faces, so even after rain stops some features may weep.
- The Llanberis Pass funnels moist south-westerly airflow directly onto these boulders, and the prevailing SW wind pattern this week keeps humidity elevated.
Warnings
2
- Wet rhyolite is extremely slippery — friction loss on this rock type is sudden and severe, making falls highly likely on anything technical.
- Boggy approaches and wet landings at 300m altitude increase the risk of ankle injuries and poor pad placement.
Reasoning
With 64.5mm in the last 7 days, 8.4mm today including early-morning showers, and humidity averaging 86%, rock surfaces are thoroughly wet with standing water likely in features and on landings.
Despite moderate SW winds (22–31 km/h), persistent cloud cover and high humidity (83%+) have prevented meaningful drying between rain events, and the brief dry window today (06:00–16:00) is too short and too overcast to dry saturated surfaces.
Rhyolite is non-porous so there is no structural weakening concern, but friction loss on wet volcanic rock is severe and the primary hazard.
Early June should offer improving conditions, but this spell of unsettled Atlantic weather is unusually persistent; temperatures are well below seasonal norms (11–13°C vs typical 17–20°C), further slowing evaporation.
Contributing Factors
7
64.5mm in the past 7 days with significant events on June 1 (23.5mm), June 3 (11.1mm), June 4 (11.4mm), June 7 (8.2mm), and June 8 (20.6mm) have kept surfaces continuously wet.
8.4mm total today with showers in the early morning and again from 16:00 onwards means no sustained drying window.
Average humidity of 86% over the past week with persistent cloud cover drastically reduces evaporation rates.
Temperatures of 11–13°C are well below late-May/early-June norms for Snowdonia, further slowing surface drying.
Winds of 20–31 km/h provide some air movement to aid drying, but high moisture content in the SW airflow limits the benefit.
The south aspect would normally aid drying, but heavy cloud cover (80–100%) throughout this period negates the solar advantage.
22.3mm forecast for June 11 and 8.0mm for June 12 mean conditions will worsen again before any chance of drying.
Recommendations
3
- Wait for a sustained dry spell — conditions are unlikely to be climbable before June 14 at the earliest, when a dry window with warming temperatures may finally allow proper drying.
- If visiting the Llanberis Pass area, consider checking roadside crags with overhanging or sheltered faces that may have stayed dry, but verify conditions visually.
- Monitor the forecast closely around June 13–14; if the dry window materialises with sunshine and the predicted 20°C+ temperatures, the south-facing rhyolite could dry within a few hours of direct sun.
Do Not Climb
90%
9 days ago
Wavelength Boulders are currently saturated after 26mm of rain today on top of over 60mm in the past week. Even though the afternoon looks dry, the rock will be wet and slippery, and the forecast offers no meaningful drying window for the next several days.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The 15–20 minute uphill approach means the boulders sit in the hillside above Nant Peris, where drainage and seepage from saturated ground above can keep holds wet long after rain stops.
- South-facing aspect is helpful for drying, but persistent cloud cover (50–100%) and high humidity today severely limit solar drying effectiveness.
- The stratified rhyolite formations can trap water in horizontal cracks and layered features, meaning surface-dry rock may still have wet seepage lines.
- At 300m altitude with recent temperatures barely above 10°C, evaporation rates are slow and overnight condensation/mist is very likely given 85%+ humidity.
Warnings
2
- Rhyolite is extremely slippery when wet — a fall from even low-height bouldering problems on greasy rock can cause serious injury.
- The steep uphill approach will be slippery and muddy after this prolonged wet spell; take care on the path even if only scouting conditions.
Reasoning
The rock is thoroughly wet after 26mm of heavy rain overnight and early morning today, compounding 62mm over the past week with no consecutive dry days.
Although rain stops around 07:00 and a dry window opens until 18:00, high humidity (55–65%), moderate SW wind, and limited sunshine at 300m altitude will only partially dry exposed surfaces — deep features and seepage lines will remain wet.
Rhyolite is non-porous and not at risk of structural damage from moisture; the concern is purely friction loss on wet or damp surfaces.
Early June in Snowdonia is experiencing an unusually wet and cool spell with temperatures 5–10°C below seasonal norms, significantly slowing drying and increasing condensation risk.
Contributing Factors
7
26mm of rainfall today, with the heaviest falling overnight and into early morning, has thoroughly soaked all boulder surfaces.
Over 62mm in the past 7 days with zero consecutive dry days means the ground and rock features are saturated with no recovery period.
Humidity averaging 86% over the past week and forecast to remain 55–85% today limits evaporative drying significantly.
A roughly 10-hour dry spell from 07:00–18:00 today with partial cloud breaks offers some surface drying, but is insufficient after this volume of rain.
The southerly aspect would normally aid drying, but heavy cloud cover and cool temperatures today largely negate this advantage.
SW winds of 17–19 km/h through the afternoon will help surface moisture evaporate on exposed faces.
The next 5 days forecast an additional 26mm of rain with no extended dry period, preventing any meaningful recovery.
Recommendations
3
- Do not visit today or in the coming days — the boulders are wet and the forecast offers no drying window until at least June 14th.
- Consider lower-altitude roadside venues with better shelter if you must climb this week, but check conditions carefully on arrival.
- Monitor the forecast from June 14th onwards — if the dry spell materialises, the south-facing aspect and wind exposure should allow rapid drying within 24 hours of rain stopping.
Do Not Climb
95%
10 days ago
The Wavelength Boulders are currently saturated after 68mm of rain in the past week, with 16.5mm falling today and a further 102mm forecast over the next five days. Even on non-porous rhyolite, persistent surface water, seepage, and extremely high humidity will make conditions dangerously slippery.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The south-facing aspect would normally aid drying, but the relentless incoming rain and cloud cover over the next five days negate any solar benefit.
- The 15–20 minute uphill approach means conditions can differ from the road — mist and low cloud frequently sit at 300m in the Pass during prolonged wet spells, keeping surfaces damp even without direct rain.
- Stratified rhyolite formations at this venue create natural channels and ledges that pool and hold surface water longer than smooth faces, requiring extra drying time after heavy rain.
- Some problems here sit beneath overhangs or in sheltered alcoves that may stay drier, but seepage from saturated ground above can drip onto holds for days after heavy rain.
Warnings
3
- Active heavy rain today and forecast tomorrow — rock surfaces will be dangerously slippery and streams may be in spate on the approach.
- The steep uphill approach to these boulders will be slippery and potentially hazardous in sustained wet conditions — take care on grassy slopes.
- A major 52mm rain event is forecast for June 11; avoid any plans for that day and allow at least 24 hours of dry weather afterwards.
Reasoning
The rock is currently wet from 16.5mm of rain today on top of 68mm over the past week, with humidity at 91% leaving no opportunity for surface evaporation.
Despite partial wind exposure and a south-facing aspect, the continuous rain cycle — with 21mm forecast tomorrow and heavy rain through June 12 — means no meaningful drying window exists in the foreseeable future.
Rhyolite is non-porous and structurally unaffected by moisture, so hold breakage and rock damage are not concerns here.
Early June should offer reasonable conditions, but this is an unusually wet and cool spell with temperatures well below seasonal averages, prolonging surface moisture retention.
Contributing Factors
6
68mm in the last seven days with 16.5mm today has left all surfaces thoroughly wet with active runoff and seepage.
Over 100mm is forecast in the next five days, including a 52mm deluge on June 11, ensuring conditions will worsen before they improve.
Humidity has averaged 88% over the past week and remains above 80% in the forecast, severely inhibiting surface evaporation.
Rhyolite does not absorb water or suffer structural damage, so once a dry window arrives the rock will recover relatively quickly.
The south-facing aspect and moderate wind exposure are normally beneficial for drying, but are irrelevant during continuous rain and overcast skies.
Temperatures around 12–13°C are below seasonal norms, reducing evaporation rates during any brief dry gaps.
Recommendations
3
- Do not visit until a sustained dry spell of at least 24 hours with lower humidity arrives — potentially not before June 13 at the earliest.
- Monitor forecasts closely around June 13 onwards; if the dry window materialises, the south aspect and wind should allow the rhyolite to dry within a day of rain stopping.
- If you do travel to the Llanberis Pass area, consider visiting an indoor wall or a well-sheltered slate venue instead during this prolonged wet spell.
Do Not Climb
92%
11 days ago
The Wavelength Boulders are currently wet and will remain so for the foreseeable future. Over 56mm of rain has fallen in the past week — including 23.5mm on June 1st and further significant rain on June 3rd, 4th, and today — with no meaningful dry window, and the five-day forecast shows continuous rain totalling nearly 39mm more.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The 15–20 minute uphill approach means conditions at the boulders can differ from roadside — the higher altitude (300m) and exposure to cloud/mist can keep humidity elevated even when the valley floor feels drier.
- Stratified rhyolite formations can channel and trap water in horizontal seepage lines and between layers, meaning some problems will retain surface moisture longer than smooth faces despite the rock being non-porous.
- The south-facing aspect is an advantage for drying when the sun appears, but persistent cloud cover and high humidity (averaging 88% this week) negate that benefit almost entirely.
- Landings below the boulders will be saturated and potentially muddy/slippery after this prolonged wet spell, increasing the risk of pad slippage on steeper ground.
Warnings
2
- Rhyolite is extremely slippery when wet — the friction that makes these boulders exceptional in dry conditions disappears entirely, creating a serious fall risk.
- Saturated landings on the hillside will be muddy and unstable, increasing the chance of pad movement and ankle injuries on descent or falls.
Reasoning
With 7.8mm falling today on top of 56mm in the past week and no consecutive dry days, the rock surfaces will be wet or at minimum damp across the venue.
Despite the south aspect and partial wind exposure, persistent high humidity (87–95%) and continuous rainfall have prevented any meaningful drying; the rock has had no opportunity to shed surface moisture.
Rhyolite is non-porous and does not suffer structural weakening when wet, so hold breakage is not a concern here.
Early June should be prime season, but this unseasonably wet and cool spell (averaging only 12.6°C) with very high humidity has created winter-like drying conditions.
Contributing Factors
6
Over 56mm in the past 7 days including 23.5mm on June 1st and 11mm+ on both June 3rd and 4th, with further rain today, leaves all surfaces wet.
There has been no dry window to allow surface moisture to evaporate, with rain falling on most of the past six days.
Humidity averaging 88% over the past week severely inhibits evaporation even on exposed south-facing rock.
The next five days show rain every day (10.5mm, 13.6mm, 3.3mm, 6.3mm, 5.1mm), with no prospect of a drying window.
Temperatures averaging only 12.6°C — well below seasonal norms — further slow any evaporation from rock surfaces.
The south-facing aspect and moderate wind exposure would normally aid drying, but are rendered ineffective by the persistent cloud, rain, and high humidity.
Recommendations
3
- Do not visit this week — conditions are clearly unsuitable and will not improve before at least June 12th at the earliest.
- Monitor the forecast from June 12th onwards; a full dry day with lower humidity and some sunshine would be needed before the rock offers safe friction.
- If in the Llanberis area, consider indoor alternatives or well-sheltered sport limestone venues where wet holds are less consequential than on friction-dependent rhyolite bouldering.
Climbing Outlook