Condition Analysis
AI-powered assessment using site data and 14-day weather history
Sheep Pen Boulders are currently wet and unsuitable for climbing. A prolonged spell of heavy rain over the past two weeks (110mm in 28 days), rain today, and a very wet forecast through to June 21st mean the rock will remain wet or damp with no meaningful drying window in sight.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The exposed plateau position normally aids rapid drying, but persistent cloud cover and high humidity (83% average over the last week) are negating the wind-drying advantage.
- At 400m altitude the site is frequently in cloud during this weather pattern, which can deposit condensation on rock surfaces even between rain showers.
- The west-facing aspect means afternoon sun could help, but 100% cloud cover forecast today and in coming days blocks any solar drying.
- The steep scree approach will be slippery and potentially hazardous in these wet conditions — extra care needed even on the walk-in.
Warnings
3
- The scree approach is hazardous in wet conditions — avoid the walk-in during or immediately after rain.
- Wet rhyolite is extremely slippery; bouldering falls from even moderate height onto wet ground carry elevated injury risk.
- At 400m, cloud immersion is likely in this weather pattern, which will keep surfaces damp even during breaks in rain.
Reasoning
The rock is almost certainly wet: 3.9mm fell today with rain from 16:00 onwards, following 17.9mm on June 11th and only two dry days (June 12–14) before further rain on the 15th and today.
Despite the exposed position and moderate winds (22–33 km/h), persistently high humidity (83–92%) and overcast skies have severely limited evaporative drying, and no meaningful dry window has occurred since early June.
Rhyolite is non-porous so there is no structural weakening risk; the concern is purely surface friction loss on wet volcanic rock, which is significant for bouldering where every hold matters.
Early summer in Snowdonia can bring extended Atlantic frontal systems; the current pattern of repeated wet days is typical and the forecast suggests no break until possibly June 22nd.
Contributing Factors
6
Over 110mm in 28 days with significant rain on multiple days in the past week (June 6–11), and further rain today totalling 3.9mm.
Average humidity of 83% over the last 7 days with today reaching 90–99%, preventing effective evaporative drying.
Rain arriving from 16:00 today (3.9mm total) with further rain tomorrow (1.4mm) and heavy rain through to June 21st.
The plateau catches wind well (26 km/h today) which helps surface drying, but this advantage is overwhelmed by the continuous moisture input.
100% cloud forecast for most of today and likely through the week, blocking solar drying and keeping the 400m site potentially in cloud.
The next five days show rain every day (51mm total forecast), with the first potentially dry day not until June 22nd.
Recommendations
3
- Wait for a sustained dry spell — the first possible window appears around June 22nd, but check updated forecasts.
- If visiting the Ogwen area, consider low-altitude sheltered sport venues with quick-drying overhangs as alternatives.
- Monitor conditions closely; if June 22nd delivers a full dry day with wind, a late-afternoon session could be feasible but verify on arrival.
Previous Analyses
Marginal — Assess Conditions
65%
2 days ago
After three dry days with moderate wind following a very wet period, surface rock at Sheep Pen Boulders should be largely dry by this afternoon, but the prolonged saturation of the past two weeks and persistent high humidity mean some sheltered faces and seepage spots may still be damp. A significant wet spell arrives tomorrow, so today offers the best window.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The exposed plateau position and consistent 20+ km/h winds over the past three dry days will have efficiently stripped surface moisture from most boulder faces, despite the heavy recent rainfall.
- West-facing aspects receive afternoon and evening sun — today's clearing around midday and warm afternoon temps (~19°C) should provide good drying conditions through the middle of the day.
- The preceding two-week period saw over 100mm of rain with very few dry breaks, so ground saturation is high and seepage from cracks, roofs, and north-facing holds is likely despite surface drying.
- At 400m altitude, 100% cloud cover for much of today limits solar drying; the brief clear spell around 10:00 is the exception, so wind is doing most of the drying work.
Warnings
2
- Tomorrow begins a 5-day run of rain totalling over 40mm — if you miss today's window, conditions are unlikely to be suitable again until at least June 21.
- High humidity in the evening (84–92% from 19:00 onward) may cause condensation on rock; plan to finish climbing by late afternoon.
Reasoning
Three consecutive dry days with steady wind at an exposed 400m site should have cleared surface moisture from most faces, but the 106mm in the last 28 days (including 64mm in the last 10 days) means residual dampness in cracks and sheltered areas is very likely.
The west-facing aspect gets afternoon sun and the exposed position has seen 20–35 km/h winds throughout the dry spell, providing effective surface drying despite overcast skies and moderate humidity (71% today).
Rhyolite is non-porous and not at risk of structural weakening; the concern is purely friction loss on any remaining wet surfaces.
Early June in Snowdonia is prime season but this year's weather has been exceptionally unsettled; daylight hours are long, giving a good afternoon window before humidity climbs in the evening.
Contributing Factors
6
No measurable rain since June 12 (0.1mm trace), giving surfaces three full days to dry in wind.
Consistent 20–35 km/h winds at 400m altitude are highly effective at evaporating surface moisture from the boulders.
Over 64mm fell in the 10 days before the dry spell, saturating the ground and feeding seepage lines that take longer to clear.
Humidity has averaged 81% over the past week and remains above 70% today, slowing evaporation and risking condensation on cold rock.
Near-100% cloud cover for most of today reduces radiant heating that would otherwise accelerate drying of sheltered surfaces.
14.3mm forecast for June 16 followed by further rain all week means today is the only viable climbing window for days.
Recommendations
3
- Head up this afternoon (12:00–17:00) when temperatures peak and humidity is lowest — this is the best window before tomorrow's rain arrives.
- Visually inspect and hand-test every boulder face before committing; prioritise steep overhanging problems and west-facing surfaces which will have dried fastest.
- Bring a towel for minor seepage and avoid slab or low-angle friction problems where residual dampness poses the greatest slip risk.
Marginal — Assess Conditions
60%
3 days ago
After a very wet 10-day spell (over 80mm from June 1–11), the site has had roughly two dry days with moderate wind, which should have cleared surface moisture from this exposed, non-porous rhyolite. However, high ambient humidity (81%) and the recent saturation of the surrounding ground mean seepage and residual dampness in sheltered spots remain possible — a visual check on arrival is essential.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The exposed plateau position at 400m catches strong winds from all directions, significantly accelerating surface drying on this non-porous rock even after heavy rain.
- West-facing aspect means the boulders only receive afternoon and evening sun; morning sessions may encounter lingering dew or condensation, especially with humidity above 80%.
- The surrounding peat and scree plateau can remain waterlogged after prolonged wet spells, potentially feeding seepage onto lower boulder faces and landings even when the rock surface itself is dry.
- At 400m in Snowdonia, cloud base can sit on or below the site during unsettled weather, depositing moisture directly onto the rock even without measurable rainfall.
Warnings
2
- The 15-minute scree approach can be treacherous when wet — take extra care on the descent if cloud rolls in or rain arrives.
- Cloud base at 400m in Snowdonia can deposit moisture directly onto the rock without measurable precipitation; if you climb into cloud, conditions may deteriorate rapidly.
Reasoning
Two full dry days after 17.9mm on June 11 — the non-porous rhyolite surface should be largely dry, but persistent high humidity (76–84%) will have slowed evaporation and may leave a film of moisture in sheltered or shaded areas.
Moderate to strong winds (25–32 km/h westerly) over the last two days on this exposed plateau will have driven effective surface drying despite the humidity, though the west aspect limits direct sun to afternoons only.
Rhyolite is non-porous and does not suffer structural weakening when wet; hold breakage is not a concern regardless of moisture history.
Early June in Snowdonia brings long daylight hours aiding drying, but the recent spell of cool, saturated weather (averaging only 10.9°C with 83% humidity) has kept drying rates well below summer norms.
Contributing Factors
6
Over 80mm fell between June 1–11, thoroughly saturating the plateau and surrounding ground even though the rock itself doesn't absorb water.
June 12–14 have been essentially dry with 19–32 km/h winds on this exposed site, which should have cleared most surface moisture from the rock.
Humidity has remained above 76% throughout the drying window, slowing evaporation and raising the risk of condensation on cool rock surfaces.
The perched, wind-swept position at 400m is exceptionally well-ventilated, which significantly accelerates surface drying on non-porous rock.
West-facing boulders receive direct sun only in the afternoon and evening, providing some solar drying but leaving mornings reliant on wind alone.
Rain is forecast from June 16 onwards (7.4mm, 3.1mm, 5.2mm on successive days), closing the current dry window quickly.
Recommendations
3
- Visit tomorrow (June 15) for the best window — warmer temps (20°C), lower humidity (70%), and SE winds should give the driest conditions this week.
- Arrive in the afternoon rather than the morning to allow sun and wind to clear any overnight dew or condensation from the west-facing rock.
- Physically touch-test holds and friction-test the rock before committing to harder problems; if the surface feels greasy or slick, wait or move to steeper overhanging faces where seepage is less likely.
Marginal — Assess Conditions
55%
4 days ago
After a very wet 10-day spell culminating in 17.9mm on June 11, the site has had only ~1.5 dry days with moderate westerly winds; the exposed position and non-porous rhyolite mean surfaces may have dried, but seepage and sheltered faces could still be damp. Tomorrow (June 15) looks like the best window before more heavy rain arrives mid-week.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The plateau's fully exposed position at 400m catches strong prevailing winds, which accelerates surface drying significantly on this non-porous rhyolite — but also means cloud and mist can roll in quickly from the Ogwen Valley, re-wetting surfaces.
- Some boulder problems sit in hollows or have north-facing aspects that won't benefit from the westerly aspect's afternoon sun, so drying will be uneven across the site.
- The steep scree approach can be treacherous when wet — the recent prolonged rain may have left the approach loose and slippery, so take extra care on the 15-minute walk-in.
- At 400m altitude with recent humidity averaging 84%, overnight condensation and lingering dampness in cracks and scoops is very likely even when main faces appear dry.
Warnings
2
- The steep scree approach will be loose and potentially slippery after prolonged wet weather — take extra care and allow additional time.
- At 400m, cloud can envelop the plateau rapidly even on apparently clear days, instantly re-wetting rock surfaces and reducing visibility for the descent.
Reasoning
After 52.4mm in the last 7 days including 17.9mm just two days ago, only one full dry day with moderate wind has elapsed — surface moisture on exposed faces is likely gone but sheltered areas, scoops, and lower surfaces may still be damp.
Today's dry conditions with 24.5 km/h westerly winds on a west-facing exposed site provide good drying for directly exposed surfaces, but the high humidity (80%) limits evaporation efficiency and one day is marginal after such a wet spell.
Rhyolite is non-porous and does not suffer structural weakening when wet, so hold breakage is not a concern.
Early June in Snowdonia brings long daylight hours aiding drying, but the current unsettled Atlantic weather pattern with high humidity and frequent frontal systems is limiting useful drying windows.
Contributing Factors
6
Over 52mm in the last 7 days with significant falls on June 8 (19.4mm) and June 11 (17.9mm) have saturated the surrounding ground and left residual moisture across the site.
The fully exposed position at 400m with consistent 20–35 km/h winds accelerates surface drying on this non-porous rock.
Humidity averaging 84% over the last week with 80% today significantly slows evaporation and increases the risk of condensation on cool rock surfaces.
The volcanic rock does not absorb water, so only surface moisture and trapped water in features need to evaporate.
Only ~1.5 consecutive dry days since the last significant rain, which is marginal for full drying of all boulder surfaces including sheltered areas.
Heavy rain forecast from June 16 (7.8mm) through June 17 (23.2mm) and June 18 (7.7mm) will re-wet the site before conditions can fully recover.
Recommendations
3
- If visiting today or tomorrow, carefully check each boulder problem for residual moisture in scoops, horizontal breaks, and north-facing surfaces before committing — many problems should be climbable but conditions will vary.
- Target June 15 as the best day this week: the forecast is dry with lower humidity (71%), warming temperatures, and moderate winds — this is likely the only good window before mid-week rain.
- Bring a towel and soft brush; avoid problems with visible seepage or standing water in holds, and be prepared to walk away from damp lines.
Do Not Climb
35%
5 days ago
The Sheep Pen Boulders have been subjected to a prolonged wet spell with 63.5mm in the last 7 days alone, including 17.9mm just yesterday and heavy rain on most recent days. Despite the site's exposed position and fast-drying reputation, today is effectively the first dry day and high humidity (84%) will severely limit drying — the rock is very likely still wet or damp in many areas.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The plateau's exposed, wind-swept position normally accelerates drying significantly, but persistent high humidity (85% average over the last week) reduces the effectiveness of wind-driven evaporation.
- At 400m altitude with a west aspect, the boulders will be in cloud or mist during many of these humid, unsettled days, meaning surfaces may be wet even between recorded rain events.
- The steep scree approach can be treacherous when wet — the last week's heavy rain will have left the approach slippery and potentially hazardous.
- Some problems on the west-facing aspects will catch afternoon sun and dry faster, but overhanging or sheltered faces and lower landings may retain moisture longer despite the generally non-porous rock.
Warnings
2
- Rock surfaces are very likely still wet or greasy today following 63.5mm of rain in the past week — climbing on wet rhyolite is extremely slippery and risks serious falls.
- The steep scree approach will be hazardous in current damp conditions.
Reasoning
With 17.9mm falling yesterday (June 11), 19.4mm on June 8, and only a trace of dry weather today, rock surfaces across the plateau are almost certainly still wet or carrying residual surface moisture.
Today's strong westerly wind (30 km/h) will help strip surface moisture, but 84% humidity and only partial afternoon sun on this west-facing site mean effective drying will be slow — likely needing at least one full dry day with lower humidity before surfaces are reliably dry.
Rhyolite is non-porous and does not suffer structural weakening from saturation, so hold breakage is not a concern here.
Early June in Snowdonia is prone to unsettled Atlantic weather; temperatures averaging only 11°C over the past week are below seasonal norms and further slow evaporation at this altitude.
Contributing Factors
6
63.5mm in the last 7 days with 17.9mm just yesterday means rock surfaces are almost certainly still wet across the site.
Average humidity of 85% over the past week with 84% today severely limits evaporative drying even with wind.
Strong westerly winds today (30 km/h) and the plateau's exposed aspect will accelerate surface drying compared to sheltered crags.
Rhyolite does not absorb water, so only surface moisture needs to evaporate — no internal drying required.
Today is effectively the first dry day after an extended wet period, providing insufficient drying time for reliable friction.
Temperatures averaging only 11°C at 400m reduce evaporation rates and make condensation more likely on rock surfaces.
Recommendations
3
- Wait at least one full dry day with lower humidity before visiting — tomorrow (June 13) looks promising if humidity drops as forecast, but assess on arrival.
- If you do visit, prioritise steep and overhanging west-facing problems that catch afternoon sun and shed water quickly.
- Check the scree approach carefully — it will be slippery after the prolonged wet spell, and take extra care on the descent.
Do Not Climb
95%
6 days ago
Sheep Pen Boulders are currently soaked after nearly 66mm of rain in the last 7 days, with heavy rain continuing throughout today (19.5mm forecast). Despite the exposed position aiding drying, the sustained wet spell and near-100% humidity mean the rock will be thoroughly wet and dangerously slippery.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The plateau's exposed position and wind catch normally allow rapid drying, but persistent high humidity (85%+ average over the past week) severely limits evaporation even with strong winds.
- At 400m altitude with a west aspect, the site is directly in the path of the prevailing SW weather systems that have been delivering repeated frontal rain over the past 10 days.
- The steep scree approach will be particularly treacherous in current wet conditions — loose volcanic scree becomes very slippery when wet.
- Rhyolite at Sheep Pen offers exceptional friction when dry but becomes extremely slick when wet, and with problems graded V4–V12 the margin for error on technical moves is very small.
Warnings
3
- Active heavy rain today with 19.5mm forecast — rock will be dangerously slippery.
- The steep scree approach is hazardous in wet conditions; risk of slips and ankle injuries is high.
- At 400m with near-100% humidity, cloud immersion is likely — visibility may be very poor on the plateau.
Reasoning
The rock is thoroughly wet — 65.7mm fell in the last 7 days with heavy rain today (19.5mm), and humidity has been at or above 90% for days, leaving surfaces saturated.
Despite the exposed position and moderate winds (20–35 km/h), the near-constant humidity above 85% and 100% cloud cover have prevented meaningful drying between rain events over the past 10 days.
Rhyolite is non-porous and not at risk of structural damage from moisture, so the concern is entirely friction loss and climber safety.
Early June should offer improving conditions, but this has been an unusually prolonged wet spell; at 400m the temperatures are modest (10–13°C) which slows evaporation.
Contributing Factors
6
Nearly 66mm in the last 7 days with no consecutive dry days means surfaces have had no opportunity to dry.
A further 19.5mm is falling today with the heaviest showers through mid-morning to early afternoon, keeping the rock thoroughly wet.
Humidity has averaged 85% over the past week and is at 94–100% today, virtually halting surface evaporation.
Strong winds (23–35 km/h) at the exposed plateau help strip surface moisture quickly once rain stops and humidity drops.
Rhyolite does not absorb water, so once surface moisture evaporates the rock will be climbable — no extended internal drying period needed.
Complete cloud cover today eliminates solar heating, which would otherwise help drive off surface moisture.
Recommendations
3
- Do not visit today — the rock is actively wet and the approach scree will be dangerously slippery.
- The earliest realistic window is June 14th if the forecast dry day materialises, but check humidity and cloud cover before committing to the walk in.
- Monitor conditions closely around June 15–17 when lower humidity and stronger winds may finally allow proper drying.
Do Not Climb
90%
8 days ago
The Sheep Pen Boulders are currently wet and unsuitable for climbing after a prolonged spell of heavy rain totalling over 60mm in the last week, with further showers today and in the forecast. Although rhyolite dries relatively quickly and the exposed plateau helps, the persistent high humidity (83–90%) and ongoing precipitation mean surfaces will not achieve the friction needed for safe bouldering.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The plateau's exposed position and westerly wind will accelerate surface drying once rain stops, but at 400m with 86% average humidity the rock may remain damp between showers.
- Seepage and pooling on boulder tops and in cracks can persist longer than open faces dry, particularly after 60mm+ in a week — check landings and top-outs carefully.
- The steep scree approach becomes slippery and unpleasant in wet conditions; allow extra time and take care on descent.
- At 400m the site is frequently in low cloud during unsettled westerly weather patterns, which deposits additional surface moisture even without measurable rain.
Warnings
3
- Rhyolite becomes extremely slippery when wet — friction-dependent boulder problems at V4–V12 are dangerous on damp rock.
- The scree approach is hazardous in wet conditions; take extra care and consider microspikes if ground is muddy.
- Low cloud at 400m may reduce visibility and deposit moisture even in nominally dry forecast windows.
Reasoning
With 61.8mm in the last 7 days, rain today, and persistent humidity above 80%, rock surfaces are almost certainly wet or at best intermittently damp.
The exposed W-facing aspect and 20–35 km/h winds would normally dry rhyolite surfaces within hours, but continuous rain events and high humidity are preventing any sustained drying window.
Rhyolite is non-porous and does not suffer structural damage from moisture, so hold breakage is not a concern.
Early June should offer improving conditions, but this spell of Atlantic weather is unseasonably wet and cool, with temperatures barely reaching 11°C at altitude.
Contributing Factors
6
Over 60mm in the last 7 days across multiple rain events means the rock and surrounding ground are thoroughly saturated.
Nearly 6mm forecast today in scattered showers, with rain at 04:00, 16:00, 18:00, and 19:00 preventing sustained drying.
Average humidity of 86% over the past week with 83% today severely limits evaporative drying at 400m.
Strong 20–35 km/h winds at the exposed plateau help strip surface moisture quickly during any dry intervals.
Rhyolite does not absorb water, so once rain stops and humidity drops the surface can dry rapidly.
Temperatures of 8–11°C at 400m reduce evaporation rates compared to valley-floor readings.
Recommendations
3
- Wait for the prolonged dry spell forecast from June 14–15 before visiting; two consecutive dry days with dropping humidity should deliver excellent friction.
- If you travel to the area before then, have a low-altitude or indoor backup plan — the Ogwen Valley crags will all be similarly affected.
- Check the UKC or local social media for real-time condition reports before committing to the steep approach in marginal weather.
Do Not Climb
85%
9 days ago
Heavy rain today (nearly 20mm) on top of a very wet week (57mm in 7 days) means the rock is thoroughly soaked. Although there is a dry window this afternoon, the surfaces will still be wet and slippery from overnight and early-morning downpours, with more rain returning this evening and throughout the coming days.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Sheep Pen's exposed plateau position and constant wind help it dry faster than sheltered Ogwen crags, but even this advantage cannot overcome the sustained saturation of the past week.
- At 400m altitude with westerly aspect, the boulders may be in and out of low cloud throughout this wet spell, maintaining surface moisture even during nominal dry spells.
- The steep scree approach will be treacherous in wet conditions — loose volcanic rock on steep ground becomes very slippery and increases the risk of a slip on the walk in.
- The high-grade nature of the problems (V4–V12) demands excellent friction; even a thin film of residual moisture on rhyolite at this level is a serious safety concern for dynamic moves on steep rock.
Warnings
3
- Rhyolite becomes extremely slippery when wet — high-grade bouldering on damp surfaces risks serious falls.
- The steep scree approach is hazardous in wet conditions; take extra care on the walk in and out.
- Cloud base may be at or below 400m during this unsettled spell, reducing visibility and maintaining surface dampness.
Reasoning
The rock is saturated on the surface after 19.7mm today, 4.6mm yesterday, and 11.1mm the day before — the past week has delivered nearly 57mm with no meaningful dry period.
A dry window from roughly 07:00–18:00 today with moderate SW winds (~18 km/h) and dropping humidity (to ~55%) could begin surface drying, but a few hours of wind cannot overcome a week of persistent rain at this altitude.
Rhyolite is non-porous so there is no structural weakening risk; the concern is entirely about surface friction loss on wet or damp rock.
Early June at 400m in Snowdonia is experiencing a prolonged unsettled spell with temperatures well below seasonal norms (11–13°C), slowing evaporation significantly.
Contributing Factors
7
Nearly 20mm of rain fell overnight and into early morning, thoroughly wetting all surfaces.
57mm over the past 7 days with no consecutive dry days means the rock and surrounding ground have had no chance to fully dry.
A roughly 10-hour dry spell from 07:00–18:00 with moderate wind and lower humidity offers some drying potential.
Sustained 17–20 km/h SW winds across the open plateau will accelerate surface evaporation during the dry window.
Average humidity around 86% over the past week and 100% cloud cover overnight severely limits drying efficiency.
Temperatures around 10–12°C are well below seasonal averages, reducing evaporation rates.
Rain returns this evening and every day through at least June 12, preventing any sustained drying period.
Recommendations
3
- Wait for a sustained dry spell of at least 24 hours with wind before visiting; the current forecast does not offer this until possibly June 14.
- If you do visit during a dry window later this week, test friction carefully on easy low problems before committing to harder lines.
- Check the scree approach conditions carefully — it will be very slippery after this much rain.
Do Not Climb
92%
10 days ago
The Sheep Pen Boulders are currently soaked after nearly 60mm of rain in the past week, with 10mm falling today and significantly more forecast over the coming days. Despite the exposed position and non-porous rock, persistent high humidity (88% average) and ongoing rainfall mean surfaces will be wet and dangerously slippery.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The plateau's exposed position and wind catch aid drying, but sustained high humidity above 85% and near-daily rainfall negate this advantage in the current spell.
- At 400m altitude, temperatures are running well below seasonal norms (around 12°C) which further slows evaporation and keeps surfaces damp.
- The west-facing aspect means boulders only receive afternoon and evening sun, and with persistent cloud cover and rain, meaningful solar drying has been minimal.
- The steep scree approach will be slippery and unpleasant in these wet conditions — take extra care on the 15-minute walk in.
Warnings
2
- Rock surfaces will be extremely slippery — rhyolite loses its renowned friction entirely when wet, creating serious fall risk on steep boulder problems.
- The scree approach is hazardous in wet conditions; loose rock and wet grass increase the risk of slips on the steep hillside.
Reasoning
With 10mm today on top of 50mm in the preceding six days, rock surfaces are wet and seepage from cracks and overlaps is likely active across the boulderfield.
Despite strong winds (35 km/h SW today), the continuously high humidity (88–92%) and repeated rainfall events have prevented any meaningful drying cycle from completing.
Rhyolite is non-porous and structurally unaffected by moisture, so there is no hold-breakage concern — the risk is purely friction loss on wet surfaces.
Early June should offer improving conditions, but this is an unusually wet and cool spell; temperatures at 400m are more reminiscent of late autumn than early summer.
Contributing Factors
6
Nearly 60mm has fallen in the past seven days with 10mm today, keeping all surfaces thoroughly wet.
Average humidity of 88% over the past week prevents effective evaporation even between showers.
Over 73mm is forecast in the next six days, including 17.5mm tomorrow and 32.5mm on June 11, with no sustained dry window.
Strong winds (22–44 km/h forecast) help strip surface moisture, but cannot overcome continuous re-wetting.
Temperatures around 11–13°C at 400m altitude significantly reduce evaporation rates.
Rhyolite does not absorb water, so only surface drying is needed — but surfaces must actually be dry for safe friction.
Recommendations
3
- Avoid climbing at Sheep Pen Boulders for the foreseeable future — the entire coming week looks wet with no viable dry window.
- Consider lower-altitude sheltered crags or indoor walls until this unsettled spell passes.
- Monitor forecasts for a sustained dry period of at least 24 hours with wind and lower humidity before returning; the exposed position means the rock can dry rapidly once conditions allow.
Do Not Climb
92%
11 days ago
The rock is almost certainly wet today following 12.3mm of rain with high humidity (89%), and conditions will not improve over the coming days with persistent rain forecast throughout the week. Despite the exposed position and non-porous rock, there has been no meaningful drying window since a prolonged wet spell began on May 31st.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Sheep Pen's exposed plateau position and strong winds do aid rapid surface drying, but the relentless rain cycle (53mm in the past 7 days with more forecast) means the rock never gets a chance to dry fully.
- At 400m altitude with persistent cloud cover and temperatures barely reaching the low teens, evaporative drying is significantly slower than in lowland conditions.
- The west-facing aspect receives only afternoon/evening sun, and with overcast skies dominating, solar drying contribution is minimal during this spell.
- The steep scree approach can become treacherous in wet conditions — take extra care on the 15-minute hike up, especially in descent.
Warnings
3
- Wet rhyolite is extremely slippery — friction-dependent boulder problems become dangerous with no rope or gear to arrest falls.
- The scree approach is significantly more hazardous in wet conditions; take care and allow extra time.
- Persistent low cloud at 400m may reduce visibility on the plateau — navigate carefully.
Reasoning
The rock is wet — 12.3mm fell today on top of heavy rain on June 1st (17.1mm), June 3rd (8.8mm), and June 4th (10.9mm), with humidity consistently around 89–92%.
Strong winds (40 km/h today) would normally help dry non-porous rhyolite quickly, but with no break in precipitation and near-saturated air, surface moisture cannot evaporate effectively.
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 unusually wet and cool spell with temperatures 5–10°C below seasonal norms is preventing the rock from drying.
Contributing Factors
6
53mm in the last 7 days with 12.3mm today alone means the rock surfaces are saturated with standing water.
Humidity averaging 88% over the past week severely inhibits evaporative drying even in wind.
Every day through June 11th shows further rainfall (totalling ~34mm), with no dry window to allow surfaces to clear.
The exposed plateau catches strong winds (20–40 km/h) which would strip surface moisture rapidly if rain stopped and humidity dropped.
Temperatures of 10–14°C at 400m with persistent cloud reduce thermal drying significantly.
Rhyolite does not absorb water so only surface moisture needs to clear, meaning recovery will be fast once dry weather arrives.
Recommendations
3
- Wait for the wet spell to break — the earliest possible dry window appears to be around June 12th, but check updated forecasts closer to the time.
- If visiting the Ogwen Valley area, consider using the time to scout approaches and familiarise yourself with the plateau location rather than climbing.
- When conditions do improve, the exposed position and strong winds mean the rhyolite could be climbable within hours of rain stopping, provided humidity drops below 75%.
Climbing Outlook