Condition Analysis
AI-powered assessment using site data and 14-day weather history
The rock is currently wet from heavy rain today (22.8mm) with persistent showers throughout the morning and early afternoon. The forecast shows a sustained multi-day rain event through August 30th, with no meaningful drying window expected until September 1st at the earliest.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Wavelength Boulders sit above the Cromlech hut on the south side of Llanberis Pass — the south aspect normally aids drying, but during prolonged frontal rain with 100% cloud cover the aspect advantage is negligible.
- The 15–20 minute uphill approach means the boulders sit at ~300m where orographic enhancement increases actual rainfall beyond valley-floor readings, so totals may be worse than reported.
- The stratified rhyolite formations can hold surface water in horizontal breaks and ledges between strata, meaning even after rain stops these features may seep for hours.
- High-quality friction-dependent problems like Wavelength (V8) become dangerously slippery when wet — rhyolite's renowned grip disappears entirely on damp surfaces.
Warnings
2
- Wet rhyolite is extremely slippery — do not attempt friction-dependent problems even if the rock appears surface-dry during brief lulls in rain.
- The uphill approach to the boulders will be waterlogged and slippery; take care if visiting to inspect conditions.
Reasoning
The rock is thoroughly wet: 22.8mm has fallen today with rain through midday and early afternoon, on top of 17.4mm on Aug 20th, 4.5mm on Aug 21st, and recent lighter showers — the boulders are saturated on every surface.
Despite the south aspect and partial wind exposure, there has been no meaningful drying window today (100% cloud, high humidity 85–93%, light winds during rain), and none is forecast until potentially September 1st.
Rhyolite is non-porous so there is no structural concern, but friction loss on wet surfaces makes climbing extremely dangerous, especially on the technical slab and wall problems this venue is known for.
Late August in Snowdonia is entering the wetter autumn transition; the current multi-day frontal system with 65.9mm forecast over the next 6 days is typical of this seasonal shift.
Contributing Factors
5
22.8mm of rain today with showers persisting through the afternoon means all rock surfaces are thoroughly wet.
16.8mm, 18.9mm, 16.6mm, and 11.0mm are forecast for the next four days respectively, with no drying window.
Humidity has been 83–96% for the forecast period, preventing any effective evaporative drying even during brief dry spells.
Persistent 100% cloud cover and rain eliminate the usual solar drying advantage of the south-facing aspect.
Partial wind exposure at 300m could aid drying in dry spells, but with continuous rain and high humidity the wind carries moisture rather than removing it.
Recommendations
3
- Do not visit until at least September 1st — the prolonged rain event makes climbing impossible and the approach will be boggy and unpleasant.
- Monitor conditions closely from August 31st onwards; if the 2.6mm forecast reduces to zero and winds stay strong, a late-afternoon session on September 1st may become viable.
- Consider lower-altitude indoor alternatives or sheltered sport venues during this extended wet spell.
Previous Analyses
Likely Safe to Climb
85%
57 days ago
Three consecutive dry days with today's low humidity (38–56%) and south-facing sunshine have given the rhyolite excellent drying conditions since the last significant rain on Aug 21. Today offers a superb window for bouldering, but conditions will deteriorate significantly from midweek as heavy rain moves in.
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 above the valley floor and benefit from better air circulation, aiding drying.
- Some of the stratified rhyolite formations can hold minor seepage in horizontal breaks after heavy rain periods — check layered features on arrival despite overall dry conditions.
- The south aspect receives strong August sun through the afternoon, making the mid-to-late afternoon window ideal for both drying and friction as temps cool slightly.
- The heavy rain of Aug 17–21 (34+ mm cumulative) could still feed localised seepage from hillside drainage above certain boulders, even after three dry days.
Warnings
1
- Conditions will deteriorate sharply from Aug 26 onward with heavy rain forecast — do not plan multi-day trips assuming dry rock beyond tomorrow.
Reasoning
Three full dry days following the last rain on Aug 21 (4.5 mm), combined with today's low humidity (down to 38%) and full sunshine, should have evaporated all surface moisture from this non-porous rhyolite.
The south-facing aspect has received direct solar radiation across three dry days with moderate winds (13–20 km/h), providing above-average drying conditions for an exposed 300m crag.
Rhyolite is non-porous and not structurally weakened by moisture — there is no hold-breakage or surface-damage concern.
Mid-to-late August offers reasonable daylight hours and warm temperatures; today's conditions are unusually good for Snowdonia but a significant wet spell is forecast from Aug 26 onward.
Contributing Factors
6
No measurable precipitation since Aug 21, giving non-porous rhyolite ample time to shed all surface moisture.
Humidity drops to 38% this afternoon with clear skies — outstanding evaporation conditions for Snowdonia.
Full south-facing exposure under 0% cloud cover today maximises solar drying of the rock surface.
Over 30 mm fell between Aug 17–21, which could feed residual hillside seepage into cracks and horizontal breaks on some boulders.
Partial wind exposure with 15–20 km/h SE winds today aids surface evaporation.
44.6 mm forecast for Aug 28 alone, meaning this dry window is short-lived and conditions will become unsafe later in the week.
Recommendations
3
- Climb today — this is the best window before a prolonged wet spell arrives midweek; aim for the afternoon when humidity is lowest and friction is best.
- Inspect layered and horizontal crack features for residual seepage before committing to harder problems.
- Tomorrow (Aug 25) also looks excellent — if you can't make today, plan for tomorrow as the last reliable dry day.
Marginal — Assess Conditions
62%
58 days ago
After significant rain on Aug 20–21 (nearly 22mm combined), two dry days with moderate temperatures should have dried most of the south-facing rhyolite surfaces, but high ambient humidity (76–82%) and the site's 300m altitude may have slowed evaporation. A visual check on arrival is warranted before committing to climb.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The south-facing aspect and 300m elevation mean the boulders receive good solar radiation through the day, which helps dry surfaces relatively quickly after rain — but seepage from the hillside above can persist in cracks and overlaps for longer than expected.
- The stratified rhyolite formations at Wavelength create horizontal ledges and layered features that can trap residual moisture in recesses even when exposed faces appear dry.
- The 15–20 minute uphill approach means conditions at the boulders can differ from what you see at road level in the Pass — it is cooler, more exposed, and potentially damper at altitude.
- High recent humidity (averaging 84% over the past week) limits overnight drying and can leave a thin film of condensation on the rock, particularly on shaded undersides of overhangs.
Warnings
2
- A major rainfall event of nearly 37mm is forecast for Aug 28 — do not plan climbing that day or the day after without several dry days following.
- High humidity and recent rain mean lichen-covered or shaded holds may still be slippery — test friction carefully before committing to hard moves.
Reasoning
The 22mm of rain on Aug 20–21 followed by two dry days and today's dry forecast means exposed south-facing surfaces are likely dry, but persistent high humidity (76–82%) limits full evaporation and seepage zones may still weep.
Two full dry days with south-facing aspect and partial wind exposure at moderate speeds (15–17 km/h) should be sufficient for surface drying of non-porous rhyolite, though the consistently high humidity has reduced drying efficiency.
Rhyolite is non-porous and does not suffer structural weakening when wet, so hold breakage is not a concern at this venue.
Mid-to-late August in Snowdonia brings increasingly unsettled weather patterns, and the forecast shows a return to wet conditions from Aug 25 onward, narrowing the climbing window.
Contributing Factors
6
17.4mm on Aug 20 and 4.5mm on Aug 21 delivered substantial surface water that requires adequate drying time.
Aug 22 and Aug 23 have been dry, giving south-facing rhyolite surfaces roughly 36–48 hours to shed moisture.
The southerly aspect maximises solar heating and radiation drying, which is the primary driver for surface evaporation on non-porous rock.
Humidity has averaged 84% over the past week and remains at 76% today, slowing evaporation and potentially leaving condensation on cooler rock surfaces.
Aug 24 forecasts 0mm rain, 58% humidity, 20°C, and 23 km/h SE winds — excellent drying conditions that should clear any remaining dampness.
Rain returns from Aug 25 and builds to a major 36.8mm event on Aug 28, closing the window rapidly.
Recommendations
3
- Tomorrow (Aug 24) offers the best window this week — low humidity, warm temperatures, and a drying breeze should produce excellent friction; arrive by mid-morning to maximise conditions.
- Check seepage zones and horizontal ledges carefully before pulling on — stratified features can hold hidden moisture even when main faces are dry.
- Avoid climbing from Aug 27 onward as heavy rain is forecast; the next viable window may not appear until well after Aug 28.
Do Not Climb
45%
59 days ago
Heavy rain over the past few days (17.4mm on Aug 20, 4.5mm on Aug 21) followed by only one dry day means the boulders are very likely still damp in sheltered spots and seepage areas, despite rhyolite's non-porous nature. With humidity at 83% today and moderate temperatures, surface drying has been slow.
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 roadside impressions — check rock surfaces on arrival, especially north-facing sides of individual blocks.
- The stratified formations at Wavelength create horizontal ledges and overlaps that trap and channel water; these seepage lines can remain damp long after open faces have dried.
- South-facing aspect is beneficial for drying, but at 300m altitude in the Llanberis Pass, low cloud and mist can settle and re-wet surfaces even on nominally dry days.
- The recent prolonged wet spell (34.4mm in 7 days) will have saturated the hillside above, meaning ground seepage through and beneath boulders may persist for several days.
Warnings
2
- The stratified rock features can channel hillside seepage for days after heavy rain — test friction carefully even on apparently dry surfaces.
- Friction on damp rhyolite drops dramatically; a slip on a highball problem could result in serious injury.
Reasoning
With 17.4mm on Aug 20 and 4.5mm on Aug 21, followed by only one dry day at high humidity (83%), surface moisture is likely to persist in sheltered areas, cracks, and under overhangs despite the non-porous rock.
The south-facing aspect helps, but moderate winds (13.7 km/h from NW) and high humidity (83%) today have limited effective drying to exposed open faces only — one day is insufficient to clear all moisture after such significant recent rainfall.
Rhyolite is non-porous and does not suffer structural weakening when wet; the risk is friction loss on damp surfaces rather than hold breakage.
Late August in Snowdonia is prone to unsettled Atlantic weather; the recent wet spell is typical, and humidity levels remain elevated even on dry days at this altitude.
Contributing Factors
7
34.4mm in the last 7 days including 17.4mm on Aug 20 and 4.5mm on Aug 21 has thoroughly soaked the hillside and boulder surfaces.
A single day without precipitation is insufficient to dry all boulder surfaces, especially sheltered faces and seepage areas.
Humidity at 83% today severely limits evaporation rates, keeping damp surfaces from drying efficiently.
The southerly aspect maximises solar exposure, helping sun-facing surfaces dry faster than average.
Rhyolite does not absorb water, so drying is a surface phenomenon that proceeds faster than on porous rock types.
Partial wind exposure at 13.7 km/h provides some airflow but is not strong enough to rapidly clear moisture in high-humidity conditions.
Tomorrow and the following two days are forecast dry with dropping humidity (down to 64%), which should progressively improve conditions.
Recommendations
3
- Wait at least until tomorrow afternoon (Aug 23) to allow a second full dry day; conditions should improve significantly with lower humidity forecast.
- If visiting today or tomorrow morning, visually and physically check all holds for residual dampness before committing to problems — avoid anything with visible moisture or dark wet patches.
- Prioritise exposed, south-facing walls and avoid problems in overhangs, grooves, or near the base of boulders where seepage from the saturated hillside may persist.
Do Not Climb
70%
60 days ago
Wavelength Boulders received 8.5mm of rain today on top of significant recent rainfall (38.4mm in the past week), and the rock will still be wet or damp this evening. Tomorrow begins a dry spell, but the boulders need at least a full dry day with sun and wind to shed surface moisture reliably at 300m altitude.
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 the road — check from below before committing to the walk up.
- The stratified rhyolite formations can trap seepage in horizontal cracks and overlaps, keeping moisture present longer than smooth faces would suggest.
- South aspect is a major advantage here — direct afternoon sun accelerates drying significantly once skies clear.
- High humidity (84% average this week) at 300m slows evaporation even on nominally dry days; dew can re-wet surfaces overnight.
Warnings
2
- Rhyolite becomes very slippery when wet — do not attempt technical slab or friction-dependent problems until surfaces are thoroughly dry.
- Significant rain is forecast for August 25–26 (22.5mm combined), closing the dry window quickly.
Reasoning
With 8.5mm of rain today following 17.4mm yesterday and further rain earlier in the week, the rock surfaces are currently wet and unlikely to have dried at all today given 84% humidity and only 16°C.
The south aspect and partial wind exposure will help drying once precipitation stops, but with only moderate wind (15 km/h today from the north — not ideal for a south-facing crag) and high humidity, effective drying requires at least one full dry day with good solar exposure.
Rhyolite is non-porous and not at risk of structural damage from moisture; the concern is purely friction loss on wet or damp surfaces.
Late August in Snowdonia brings shorter days and increasingly unsettled Atlantic weather patterns; the current wet spell is typical, though a brief dry window is forecast for Aug 22–24.
Contributing Factors
6
38.4mm in the past 7 days including 8.5mm today means surfaces are thoroughly wet and seepage lines will be running.
The south-facing aspect will receive good solar radiation during the forecast dry window, accelerating surface drying from tomorrow onward.
Average humidity of 84% over the past week and 80–82% forecast for the next two days slows evaporation and promotes overnight dew formation.
Partial wind exposure provides some airflow to aid evaporation, though lighter winds forecast tomorrow (12 km/h) are less effective.
At 300m, temperatures are a couple of degrees cooler than valley level, slowing drying — forecast max of only 15°C tomorrow.
Three consecutive dry days forecast (Aug 22–24) should progressively dry surfaces, with conditions improving significantly by Aug 23–24.
Recommendations
3
- Wait until at least August 23 to allow a full day of drying after today's rain; August 24 looks most promising with 20°C, lower humidity (71%), and stronger winds.
- If visiting on August 22 or 23, test friction carefully on easy problems first — south-facing slabs may dry fastest while overhangs and cracks may retain moisture.
- Prioritise the session before the next rain front arrives on August 25 (9.6mm forecast), as the dry window is brief.
Do Not Climb
40%
61 days ago
The rock is likely wet today following rain this morning (3.6mm total) on top of a very wet recent period (16.6mm in 7 days, 43.3mm in 28 days). While rhyolite dries relatively quickly, high humidity (87%) and overcast skies at 300m will slow surface drying significantly, and seepage from the hillside above may persist.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The uphill setting means drainage from the slopes above can create persistent seepage lines on certain boulders, especially after the prolonged wet spell of the last week.
- The south-facing aspect is largely negated today by near-total cloud cover, limiting solar drying despite mid-summer day length.
- The 15–20 minute uphill approach means conditions can differ from the roadside — the boulders sit higher and are more exposed to mist and hill fog in humid conditions.
- The stratified rhyolite formations can trap water in horizontal cracks and ledges, creating localised damp patches even when main faces appear dry.
Warnings
2
- Rhyolite becomes very slippery when wet — the excellent friction that defines these problems disappears entirely on damp surfaces, creating serious fall risk on highball problems.
- The uphill approach may be boggy and slippery after the prolonged wet period; take care on the walk in.
Reasoning
Rain fell this morning (1.3mm at 07:00, plus earlier showers totalling 3.6mm today) on top of 7.6mm yesterday and 2.9mm the day before, leaving the rock surfaces almost certainly wet or damp.
Despite the south aspect, persistent cloud cover (87–100%) and high humidity (73–97%) today severely limit evaporative drying, and moderate NW winds at 300m provide only partial assistance.
Rhyolite is non-porous and not at risk of structural damage from moisture, so the concern is purely friction loss on wet surfaces.
Mid-August provides long daylight hours for drying but the current unsettled Atlantic pattern with repeated frontal systems has kept the hillside saturated.
Contributing Factors
6
16.6mm over the past 7 days including 11.4mm on Aug 4–5 and a further 12.1mm from Aug 17–19, with 3.6mm today, keeps surfaces and surrounding ground saturated.
Showers fell through the early morning with 1.3mm at 07:00 and further light rain at 15:00, meaning the rock has been repeatedly wetted today.
Average humidity of 84% over the last 7 days and 87% today significantly slows evaporative drying of surface moisture.
Cloud cover remains 82–100% throughout today, blocking the solar radiation that the south aspect would otherwise provide for rapid drying.
NW winds around 15–19 km/h provide some airflow to assist surface drying on exposed faces.
Rhyolite does not absorb water so once surface moisture evaporates, friction returns to full quality without needing extended drying time.
Recommendations
3
- Wait for a dry window — tomorrow still has 2.8mm forecast, so the earliest promising session is August 22 after a full dry day.
- If visiting today or tomorrow, bring a towel and brush but be prepared to walk away if holds feel greasy.
- Check for seepage lines on the backs of boulders and in horizontal cracks before committing to problems, especially steeper lines where a slip would be consequential.
Do Not Climb
40%
62 days ago
Recent heavy rain (7.4mm yesterday, 2.2mm today including overnight showers) combined with high humidity and limited sunshine means the rock is likely still damp in many areas. Tomorrow brings a further 14.5mm of rain, so conditions are deteriorating rather than improving.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The south-facing aspect helps drying in sunshine, but today's persistent cloud cover (70–100%) severely limits solar gain on the rock.
- The 15–20 minute uphill approach means the boulders sit above the valley floor where cloud and mist can linger, and at 300m altitude temperatures are cooler than valley-level forecasts suggest.
- Rhyolite at Wavelength has distinctive stratified formations with horizontal ledges and overlaps that can hold residual surface moisture and seepage longer than smooth faces.
- The bouldering here is friction-dependent with many slab and technical face problems — even a thin film of moisture dramatically increases the risk of slipping on this rock type.
Warnings
2
- Friction-dependent slab and face problems will be dangerously slippery; avoid these entirely until a sustained dry period.
- 14.5mm of rain is forecast tomorrow — do not plan a session for Aug 20.
Reasoning
With 7.4mm on Aug 18 and 2.2mm today (most falling overnight/early morning), plus sustained humidity above 80%, surface moisture is very likely present across most of the boulders.
Although the south aspect and moderate wind (~16 km/h) aid drying, near-total cloud cover today and humidity remaining 63–80% through the afternoon window provide only marginal drying conditions — insufficient to confidently dry surfaces after repeated recent rain.
Rhyolite is non-porous and structurally sound when wet; there is no risk of hold breakage or rock damage from climbing on damp surfaces.
Mid-August is typically a reasonable period for Welsh bouldering, but this unsettled spell with above-average rainfall and humidity is suppressing drying; the pattern looks set to continue into the coming days.
Contributing Factors
6
11.4mm on Aug 4–5, then 7.4mm yesterday and 2.2mm today create a persistently wet baseline with no meaningful dry window to recover.
Humidity has averaged 81% over the past week and remains 63–80% during today's best afternoon hours, significantly slowing evaporation.
Cloud cover stays 52–100% all day, denying the south-facing boulders the direct solar radiation they need to dry efficiently.
Winds of 15–18 km/h through the afternoon provide some airflow to assist surface evaporation, partially offsetting the high humidity.
Rhyolite does not absorb water, so once surface moisture evaporates the rock is immediately climbable with no internal dampness concern.
A further 14.5mm is forecast for Aug 20, meaning any marginal drying achieved today will be completely reversed.
Recommendations
3
- Wait for the unsettled spell to pass — conditions are unlikely to be reliably dry until Aug 23 at the earliest.
- If you do visit today, focus only on steep overhanging problems that shed water quickly, and test friction carefully before committing to anything technical.
- Check UKClimbing or local social media for on-the-ground condition reports from the Llanberis Pass before making the trip.
Do Not Climb
70%
63 days ago
Rain fell overnight (2.8mm) and the rock is likely still damp under 100% cloud cover and high humidity; although rhyolite dries quickly, current conditions at 300m with persistent overcast skies and humidity in the 80–90% range are preventing effective drying. A brief afternoon window (12:00–16:00) with dropping humidity might allow some surface drying, but further rain is forecast from tomorrow through the 21st.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The south-facing aspect is negated today by 100% cloud cover, removing the solar drying advantage these boulders normally enjoy.
- The 15–20 minute uphill approach means conditions may differ from the roadside — slightly more wind-exposed but also more moisture from cloud base at 300m.
- Stratified rhyolite formations can hold moisture in horizontal seams and layered features even when the main face appears dry.
- The forecast shows three consecutive days of rain (Aug 19–21) before a potential dry window opens on Aug 22–23.
Warnings
2
- Rhyolite friction drops dramatically when damp — falls from even low-grade problems on slick holds can cause injury.
- Do not rely on the brief dry afternoon window for harder or highball problems; residual moisture in seams and under overhangs is likely.
Reasoning
Overnight rain (2.8mm) combined with humidity above 90% and 100% cloud cover means surfaces are almost certainly damp, with residual moisture in cracks and seams.
The south-facing aspect provides no benefit today under total cloud cover; moderate westerly wind (~17 km/h) offers some evaporation but humidity in the 77–88% range through the afternoon severely limits drying efficiency.
Rhyolite is non-porous and structurally sound when wet — no risk of hold breakage or rock damage, but friction is significantly reduced on damp surfaces.
Mid-August in Snowdonia often brings unsettled Atlantic weather; the current pattern of repeated light-to-moderate rain with high humidity is typical and conditions are unlikely to improve until the dry window forecast for Aug 22.
Contributing Factors
6
Nearly 3mm of rain fell between midnight and 2am, leaving rock surfaces wet heading into the morning.
Complete overcast negates the south-facing aspect's solar drying advantage entirely.
Humidity remains 77–98% throughout the day, severely slowing evaporation from rock surfaces.
Westerly winds of 15–18 km/h provide some air movement to assist surface drying during the afternoon.
Rhyolite does not absorb water so only surface moisture needs to evaporate, and no structural damage risk exists.
4.5mm forecast tomorrow and 8.7mm on Aug 20 mean any drying today will be reversed.
Recommendations
3
- Wait for the dry window forecast on Aug 22–23 when two consecutive dry days with lower humidity should allow the rock to dry properly.
- If you visit this afternoon (12:00–16:00), test friction carefully on lower problems before committing to anything committing — the rock may feel deceptively grippy in spots while remaining slick elsewhere.
- Bring a towel and brush but be prepared to walk away; the uphill approach is worth it only if conditions are genuinely good on arrival.
Do Not Climb
40%
64 days ago
Rain fell this morning (1.6mm around 10–11am) on top of already saturated conditions with near-100% overnight humidity, and the rock is likely still damp despite a dry afternoon window. With heavy rain forecast from tomorrow through midweek, conditions are deteriorating rather than improving.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The uphill approach (15–20 mins) means conditions at the boulders can differ from the road — the higher altitude and exposed hillside can retain cloud moisture and condensation even when the pass floor appears dry.
- The south-facing aspect is helpful for drying but today's 100% cloud cover all day negates any solar benefit, so drying relies solely on moderate wind.
- The stratified rhyolite formations can hold surface water in horizontal breaks and seepage lines between layers, meaning some problems dry slower than the general surface.
- The Llanberis Pass funnels prevailing SW winds effectively, which aids drying, but the current SW flow is also bringing moisture-laden Atlantic air with very high humidity.
Warnings
2
- Rhyolite friction drops dramatically when damp — greasy conditions on steep or slab problems at this venue are a serious fall risk.
- A prolonged wet spell (20+ mm over the next 3 days) begins tomorrow; do not plan sessions for the 18th–20th.
Reasoning
The rock received 1.6mm of rain this morning and overnight humidity reached 99%, meaning surfaces are very likely still damp or at least greasy despite a dry afternoon window.
With 100% cloud cover eliminating solar drying and humidity remaining above 74% even in the best afternoon hours, meaningful drying is severely limited despite moderate SW winds.
Rhyolite is non-porous and structurally unaffected by moisture — no risk of hold breakage or rock damage from climbing when damp.
Mid-August should offer reasonable conditions, but an incoming Atlantic weather system is bringing an extended wet spell that will keep humidity and precipitation elevated for several days.
Contributing Factors
6
1.6mm fell between 10–11am on already-saturated surfaces after a night of near-100% humidity.
Humidity has been above 90% for most of the past 12 hours and only drops to around 74% in the best afternoon window, severely limiting evaporation.
100% cloud cover forecast all day eliminates solar radiation that would otherwise help dry the south-facing rock.
SW winds of 10–13 km/h through the afternoon provide some drying effect, though offset by moisture-laden air.
Rhyolite does not absorb water, so only surface moisture and friction loss are concerns rather than structural damage.
4.2mm tomorrow, 8.1mm on the 19th, and 9.0mm on the 20th mean conditions will worsen significantly before they improve.
Recommendations
3
- If you are already at the crag this afternoon (after 14:00), visually and physically test rock surfaces — some sheltered problems may have dried enough for safe friction, but do not assume conditions are good.
- Plan sessions for later in the week (22nd onwards) when the incoming wet spell clears and drying can begin.
- Bring a towel and brush but be prepared to walk away — the 15-minute approach is worthwhile only if conditions genuinely allow safe friction on the rhyolite.
Marginal — Assess Conditions
55%
65 days ago
The rock has had a good dry spell from Aug 6–13 with warm temperatures, but light rain on Aug 14 (0.5mm) and today (0.4mm) introduces some surface moisture uncertainty. The south aspect and moderate wind should allow rapid drying of such small amounts on non-porous rhyolite, but conditions should be visually checked on arrival, especially as a significant wet spell is incoming from tomorrow.
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 300m altitude brings cooler temperatures and potentially more mist/cloud contact than the valley floor.
- Some of the stratified rhyolite formations can hold water in horizontal seams and ledges even after light rain, particularly on overhanging or tiered faces.
- The south aspect is highly favourable for solar drying, and today's SW wind will reach the face directly, helping surface moisture evaporate quickly.
- A prolonged wet spell is forecast from Aug 17–20 with over 20mm of rain — today may be the last viable window for nearly a week.
Warnings
2
- A major wet spell begins tomorrow (Aug 17) with over 20mm forecast through Aug 20 — plan accordingly and do not rely on afternoon windows later this week.
- At 300m altitude, cloud base may sit on or near the boulders during the incoming frontal system, keeping rock damp even between rain showers.
Reasoning
Today's 0.4mm of rain on top of 0.5mm on Aug 14 represents very light moisture on non-porous rhyolite; with two dry days (Aug 15–16 morning) and the warm dry spell beforehand (Aug 11–13 saw 30°C and 51% humidity), surface moisture should be minimal but cannot be fully ruled out.
The south aspect receives strong solar radiation in August, and the SW wind today will directly contact the face, meaning even today's light rain should dry within a few hours given the 17.6°C temperature and 77% humidity.
Rhyolite is non-porous and does not suffer structural weakening when wet; there is no hold breakage risk from moisture.
Mid-August provides long daylight hours and reasonable temperatures for drying, though the current cooler spell (16–18°C) is less effective than the preceding heatwave.
Contributing Factors
6
Only 0.5mm on Aug 14 and 0.4mm today — trivial amounts on non-porous rock that should dry quickly with solar exposure and wind.
Aug 6–13 was essentially dry with three consecutive days above 24°C and humidity as low as 51%, leaving the rock well-dried before the recent light showers.
The south-facing aspect maximises solar drying in August, and today's SW wind blows directly onto the face, accelerating surface evaporation.
Moderate humidity slows evaporation somewhat compared to the recent hot spell, meaning light dampness may linger in sheltered spots.
A substantial front bringing 23mm over the next 5 days means today is likely the last climbing window before an extended period of poor conditions.
Rhyolite does not absorb water, so the concern is purely surface friction rather than structural damage, and drying times are short.
Recommendations
3
- Visit today if possible and visually inspect rock surfaces before committing — this may be the last viable window before a week of wet weather.
- Check horizontal ledges and stratified seams for lingering moisture, as these can trap water even after very light rain.
- Bring a towel and brush to dry any residual dampness on holds, and avoid polished or low-friction sections if any surface moisture is detected.
Climbing Outlook