Condition Analysis
AI-powered assessment using site data and 14-day weather history
Caseg Fraith is currently wet from heavy rain this morning (nearly 12mm today so far) with further heavy rain forecast for the next two days (24.5mm and 22.7mm). The rock will be saturated and slippery, with no realistic drying window in the near term.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Caseg Fraith's W/NW aspect and 350m altitude mean it sits in cloud frequently during unsettled spells, keeping humidity near saturation and preventing effective drying.
- The exposed position normally aids drying via wind, but NE winds today and tomorrow are relatively light (8–15 km/h) and will not clear moisture efficiently from west-facing rock.
- The bouldering here relies heavily on the exceptional friction of dry rhyolite — even a thin film of moisture dramatically reduces grip on these steep, friction-dependent problems.
- Roadside access near the A5 makes it easy to drive up and check conditions, but the forecast is unambiguously wet through at least August 29th.
Warnings
2
- Wet rhyolite is extremely slippery — the friction that makes Caseg Fraith exceptional in the dry vanishes when wet, creating serious fall risk on bouldering problems.
- Over 60mm of rain is forecast in the next 5 days; ground conditions around boulder landings will be boggy and potentially hazardous.
Reasoning
The rock is currently wet from 11.9mm of rain today, with the heaviest falls between 08:00–11:00, and humidity remains above 90% throughout the day.
Light NE winds (5–14 km/h) and 100% cloud cover provide minimal drying potential; the W/NW-facing rock receives no direct sun today and surfaces will remain wet.
Rhyolite is non-porous and structurally unaffected by moisture, so hold breakage and rock damage are not concerns.
Late August in Snowdonia often brings Atlantic frontal systems; the current unsettled spell with 60mm+ forecast over the next 5 days is typical of early-autumn deterioration.
Contributing Factors
5
Nearly 12mm of rain fell today, predominantly between 08:00–11:00, leaving all surfaces thoroughly wet.
Humidity has remained above 85% all day with 100% cloud cover, preventing any meaningful evaporation.
24.5mm forecast for August 27th followed by 22.7mm on August 28th means conditions will worsen before they improve.
NE winds of 8–15 km/h are below the site's typically exposed conditions and insufficient to strip moisture from the rock quickly.
Rhyolite does not absorb water so will dry relatively quickly once rain stops and wind/sun returns — no structural damage risk.
Recommendations
3
- Do not visit today or over the next two days — the rock is wet and will remain so with continuous heavy rain forecast.
- Monitor conditions from August 30th onwards; if rain eases as forecast and strong SW/W winds arrive (30+ km/h), surfaces could dry within hours.
- Check for residual seepage and puddles on landings even after the surface appears dry, as drainage from higher ground can persist.
Previous Analyses
Likely Safe to Climb
85%
57 days ago
Three consecutive dry days with an easterly breeze and low humidity this afternoon have dried the non-porous rhyolite surfaces well after the wet spell ending 21 August. Today offers excellent conditions, particularly from late morning through the afternoon, but a significant wet front arrives mid-week.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Caseg Fraith's W/NW aspect means the prevailing easterly wind today blows across rather than directly onto the faces, but the exposed position still promotes effective surface drying.
- Some sheltered recesses and north-facing overhangs near the boulders may retain residual dampness from the 17–21 August wet spell — check holds before committing to problems in shaded alcoves.
- At 350m altitude, morning dew and overnight condensation can linger on rock surfaces until mid-morning even on clear days; friction improves markedly after 10–11am.
- Roadside access off the A5 means quick retreat if conditions deteriorate, which is valuable given the heavy rain forecast from Wednesday onward.
Warnings
1
- A major wet front is forecast from 27–29 August with potentially 65mm of rain; plan your visit for today or tomorrow to avoid deteriorating conditions.
Reasoning
The last significant rain was 5.7mm on 20 August and 4.3mm on 21 August, followed by three full dry days; surface moisture on this non-porous rhyolite will have evaporated completely on exposed faces.
Moderate winds (14–24 km/h) over the last three days combined with the exposed 350m position have provided effective drying despite the W/NW aspect receiving limited direct sun; today's afternoon humidity dropping to ~40% confirms excellent surface conditions.
Rhyolite is non-porous and does not suffer structural weakening when wet, so hold breakage risk is negligible regardless of recent rain.
Mid-to-late summer provides long daylight hours and warm temperatures (peaking ~20°C today), ideal for friction climbing on the textured volcanic rock at Caseg Fraith.
Contributing Factors
5
No meaningful precipitation since 21 August, giving non-porous rhyolite ample time for surface moisture to evaporate.
Humidity drops to 39–45% through the afternoon, ensuring excellent friction on the gritty volcanic rock.
The 350m exposed site benefits from persistent airflow that accelerates surface drying even on a NW-facing crag.
Around 24mm fell over five days, but three subsequent dry days are sufficient for non-porous rock surface drying.
Up to 48mm forecast on 28 August with preceding rain on 26–27 August means conditions will deteriorate sharply from Wednesday.
Recommendations
3
- Climb today — conditions are excellent from late morning through the afternoon; aim for the 11am–6pm window when humidity is lowest and surfaces are fully dry.
- Make the most of tomorrow (25 August) as well, which is forecast dry with similar temperatures before the weather breaks.
- Avoid sheltered, deeply shaded recesses where condensation or residual seepage may linger — test holds with your hand before pulling on.
Marginal — Assess Conditions
65%
58 days ago
After a wet spell from Aug 17–21 (23.8mm over 5 days), Caseg Fraith has had two dry days with moderate wind, but the NW aspect and high humidity (78–83%) will have slowed drying. Surface rock is likely dry on exposed faces but sheltered areas and seepage lines may still hold moisture — a visual check on arrival is essential.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Caseg Fraith's NW/W aspect receives very limited direct sun, especially in late afternoon, meaning surface moisture lingers longer than at south-facing Ogwen crags.
- At 350m on an exposed pass, low cloud and mist can envelop the crag even on nominally dry days, depositing condensation that negates drying progress.
- The rough grit-like texture of the rhyolite retains excellent friction even with trace dampness, but seepage lines between blocks can remain wet for days after heavy rain.
- Roadside access from the A5 allows a quick drive-by assessment — if conditions look marginal, the sheltered Caseg boulders nearest the road tend to dry first.
Warnings
2
- Low cloud and mist can roll in rapidly at 350m, instantly wetting rock surfaces that appeared dry — be prepared to stop climbing if visibility drops.
- Rain returns from Aug 25 with a significant 19.5mm event forecast for Aug 28; this dry window is narrow and conditions will deteriorate through the week.
Reasoning
The 23.8mm of rain over Aug 17–21 was significant, but two full dry days (Aug 22–23) with exposed westerly/NW winds should have cleared most surface moisture from open faces, though sheltered recesses and north-facing surfaces at 78% humidity may retain dampness.
Wind exposure at 350m aids surface drying, and the 24 km/h NW wind on Aug 22 was helpful, but the W/NW aspect means minimal solar heating, so drying has relied almost entirely on wind evaporation rather than radiant warming.
Rhyolite is non-porous and extremely hard — no structural risk from recent rainfall; the concern is purely friction loss on any residual surface moisture.
Late August in Snowdonia brings shortening days and increasing chance of Atlantic fronts; conditions can deteriorate quickly, and the forecast shows rain returning from Aug 25 onwards.
Contributing Factors
6
23.8mm fell between Aug 17–21, with the heaviest day (8.5mm on Aug 18) only five days ago, meaning seepage and sheltered areas may not be fully dry.
Aug 22 and today (Aug 23) have been dry with zero precipitation, allowing surface drying to progress on exposed rock.
The W/NW facing aspect receives minimal direct sun, particularly in the afternoon, so drying relies heavily on wind rather than solar heating.
High exposure at 350m with consistent 12–24 km/h winds accelerates evaporation of surface moisture even without direct sun.
Average humidity of 83% over the last 7 days and 78% today slows evaporation and can deposit condensation on cold rock surfaces.
Light rain forecast from Aug 25, building to 19.5mm on Aug 28, means the current dry window is short-lived.
Recommendations
3
- Tomorrow (Aug 24) looks like the best window — arrive early, visually and tactilely check rock surfaces before committing, especially on shaded or north-facing blocks.
- Prioritise the lower roadside boulders nearest the A5, which are most sheltered from mist and tend to dry first; avoid upper blocks where seepage persists.
- Carry a towel for minor surface dampness, but if rock feels cold and clammy or shows dark wet patches, wait — conditions will not improve with rain returning from Aug 25.
Do Not Climb
45%
59 days ago
Caseg Fraith has received 24mm of rain over the past 7 days, with the last significant rainfall (5.7mm and 4.3mm) on August 20–21, giving only one full dry day so far. While today is dry with a useful NW breeze, the high humidity (81%) and NW aspect mean residual moisture in seepage lines and sheltered areas is very likely.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Caseg Fraith's W/NW aspect receives minimal direct sun, particularly in the afternoon, meaning seepage and damp patches from the recent heavy rain period (Aug 17–21) will linger longer than at sun-exposed crags.
- At 350m altitude, the crag is frequently in cloud or mist during periods of high humidity like the current 81%, which can deposit surface moisture even without measurable rain.
- The exposed position catches wind effectively, which is beneficial for drying, but the NW wind today blows directly onto the face, potentially driving any hill fog moisture onto the rock.
- The bouldering here relies heavily on the exceptional grit-like friction of the rhyolite — even a thin film of residual moisture dramatically reduces this friction advantage, making otherwise straightforward problems treacherous.
Warnings
2
- Seepage lines from the recent 24mm rainfall period may still be active, creating unexpected slippery patches even on otherwise dry-looking faces.
- At 350m with 81% humidity, hill fog or low cloud can wet the rock surface without any recorded precipitation — conditions can change rapidly.
Reasoning
With 24mm of rain in the last 7 days — including 10mm in the final two days (Aug 20–21) — and only one dry day since, surface moisture almost certainly persists in sheltered areas and seepage lines despite the non-porous rock.
The W/NW aspect receives very limited direct sun, and while the exposed position and 20 km/h NW wind aid evaporation, the consistently high humidity (84% average over 7 days, 81% today) severely slows drying.
Rhyolite is non-porous and does not suffer structural weakening when wet; the risk here is entirely friction loss on damp surfaces.
Mid-to-late August in the Ogwen Valley is entering a transitional period with shorter days and increasing rainfall; the recent wet spell is typical and drying windows can be brief.
Contributing Factors
7
24mm in 7 days with 10mm falling on Aug 20–21 means significant surface water was deposited very recently.
A single dry day is insufficient to fully clear seepage and sheltered damp patches at this altitude and aspect.
Humidity averaging 84% over the past week and 81% today inhibits evaporation and may result in condensation on the rock.
The W/NW-facing rock receives minimal direct sunlight, slowing the drying of any residual surface moisture.
The exposed 350m site with 20 km/h winds today aids surface evaporation on open faces.
Rhyolite does not absorb water, so drying is a surface-only process and faster than on porous rock types.
No rain is forecast for Aug 23–24, with humidity dropping to 65–76%, which will significantly improve conditions.
Recommendations
3
- Wait at least until August 24 when a second and third fully dry day with lower humidity (65%) and an easterly wind should substantially improve surface conditions.
- If visiting tomorrow (Aug 23), physically test friction on lower problems before committing to anything committing — touch the rock surface and check for any damp film.
- Avoid any north-facing or sheltered overhanging surfaces where seepage may persist; prioritise open, wind-exposed boulders that will have dried fastest.
Do Not Climb
35%
60 days ago
Caseg Fraith has received significant rainfall over the past five days (24.4mm in the last week), including 4.7mm today, with zero consecutive dry days and persistently high humidity (84% average). The rock is almost certainly still wet or damp, and the W/NW aspect at 350m will have received minimal drying sun; conditions are not suitable for climbing today.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Caseg Fraith's W/NW aspect at 350m means it receives very little direct sun, so surface moisture from the recent prolonged wet spell will linger longer than at lower, south-facing venues.
- The exposed position on the Ogwen pass means cloud and mist frequently envelop the crag, maintaining high ambient humidity even on nominally dry days.
- The rhyolite here has an unusually rough, grit-like texture that provides superb friction when dry but becomes treacherously slippery when damp — the texture traps thin films of water.
- Roadside access near the A5 makes it easy to drive up, check conditions visually, and retreat without a long walk-in if the rock is still damp.
Warnings
2
- Do not climb today — rain is falling and the rock will be slippery; friction loss on wet rhyolite is a serious fall hazard on boulder problems.
- The recent multi-day wet spell means even sheltered faces and overhangs may have seepage or condensation; do not assume any section is dry without checking.
Reasoning
With 4.7mm of rain today on top of 8.5mm (Aug 18), 2.7mm (Aug 19), and 5.7mm (Aug 20), the rock surface is almost certainly wet right now and has had no opportunity to dry.
The W/NW aspect receives minimal direct sun, and with humidity averaging 84% over the past week and only moderate winds, drying has been negligible between the frequent rain events.
Rhyolite is non-porous and not at risk of structural damage from moisture, so the concern is purely friction loss on wet surfaces.
Late August in Snowdonia brings increasingly unsettled Atlantic weather; the current pattern of repeated frontal rain is typical, and days are shortening, reducing drying windows.
Contributing Factors
6
4.7mm of precipitation today means the rock is actively wet with no drying window.
Over 24mm in the last 7 days across multiple rain events has kept the rock surface persistently damp.
Average humidity of 84% over the past week severely inhibits surface evaporation even between rain events.
The W/NW-facing aspect at 350m receives very little direct solar heating, which is the primary driver of surface drying.
Wind exposure (~14–27 km/h) provides some convective drying, partially offsetting the poor solar aspect.
Rhyolite does not absorb water internally, so once surface moisture evaporates the rock will be climbable without a prolonged drying period.
Recommendations
3
- Wait for at least a full dry day with moderate wind before visiting; the rock needs a sustained drying window to clear surface moisture from the recent wet spell.
- August 24 looks the most promising day in the forecast — two dry days beforehand, lower humidity (67%), and good wind — but check conditions on arrival.
- If visiting on a marginal day, test friction on low, easy landings first; the gritty rhyolite texture can feel deceptively OK when a thin moisture film is present.
Do Not Climb
90%
61 days ago
Caseg Fraith is currently wet and unsafe for climbing. Heavy rain today (10.6mm, with most falling mid-morning) follows a prolonged wet spell (25mm in the last 7 days), and the rock will remain slippery throughout the day despite the NW-facing aspect receiving some wind.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Caseg Fraith's W/NW aspect receives very little direct sun, meaning surface moisture lingers far longer than at south-facing crags in the Ogwen Valley.
- At 350m altitude the crag frequently sits in low cloud and mist, which can keep the rock damp even without measurable rainfall.
- The exposed position does help with wind-drying, but prevailing SW/W winds during this wet spell have also carried moisture directly onto the rock faces.
- Roadside access near the A5 makes it easy to drive up and do a quick visual check before committing — worth doing on marginal days.
Warnings
2
- Active rain showers throughout today make the rhyolite extremely slippery — friction-dependent boulder problems are dangerous.
- Low cloud at 350m may persist even between showers, keeping rock surfaces damp and visibility poor.
Reasoning
The rock is currently wet from today's 10.6mm of rain, with significant showers between 09:00–11:00 and again at 15:00–16:00, on top of 8.5mm yesterday and 2.7mm the day before.
Despite the exposed position aiding wind-drying, the NW aspect receives minimal direct sun and humidity remains above 80%, so effective drying will not begin until a sustained dry spell arrives.
Rhyolite is non-porous and does not suffer structural weakening when wet; the risk is purely friction loss on the slippery surface.
Mid-August should offer reasonable drying potential, but the current unsettled Atlantic pattern with repeated fronts has kept the crag persistently damp.
Contributing Factors
6
10.6mm of precipitation today, with the bulk falling in intense bursts mid-morning and mid-afternoon, leaves the rock thoroughly wet.
Nearly 25mm in the last 7 days across multiple rain events means the crag has had no opportunity to fully dry.
Average humidity of 85% over the past week and 88% today severely inhibits evaporation from rock surfaces.
The W/NW-facing rock receives very little direct solar heating, slowing surface drying considerably compared to south-facing crags.
The exposed 350m location receives consistent wind which aids surface drying once rain stops, partially offsetting the poor aspect.
Rhyolite does not absorb water, so once surface moisture evaporates the rock returns to full friction — no extended internal drying needed.
Recommendations
3
- Do not climb today — the rock is actively wet and dangerously slippery.
- Wait for August 23rd at the earliest, when a sustained dry window begins; check the rock visually on arrival.
- If visiting on a marginal day, take advantage of the easy A5 roadside access to do a touch-test on the rock before committing to problems.
Do Not Climb
85%
62 days ago
Caseg Fraith has received significant rainfall over the past three days (nearly 19mm from Aug 17–19), with rain continuing through this morning and more heavy rain forecast for the next two days. The rock will be wet and slippery, and conditions are not expected to improve until at least Aug 23.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Caseg Fraith's W/NW aspect means it catches the prevailing westerly rain directly, and the lack of direct sun means surface moisture lingers far longer than at south-facing venues.
- At 350m altitude the crag is frequently in cloud during unsettled spells, adding persistent condensation moisture even between showers.
- The bouldering here relies heavily on the exceptional friction of the gritty rhyolite surface — even a thin film of moisture dramatically reduces grip and makes many problems unsafe.
- Roadside access near the A5 makes it easy to drive up and do a quick visual check if conditions are marginal, rather than committing to a long walk-in.
Warnings
2
- The rock is actively wet today — climbing on wet rhyolite is extremely slippery and a serious fall risk, especially on bouldering problems.
- Do not be misled by a brief dry window this afternoon (11:00–17:00); the rock will still be saturated from morning rain and residual moisture.
Reasoning
The rock is currently wet from 7.8mm of rain today (mostly overnight/morning), following 8.5mm yesterday and 2.6mm the day before, with humidity at 85% and cloud cover near 100%.
Although the exposed position and moderate westerly wind help surface drying, the W/NW aspect receives no direct sun and humidity remains very high (80%+), so meaningful drying has not occurred and will not begin until the rain stops after Aug 22.
Rhyolite is non-porous so there is no structural weakening risk, but the primary concern is severe friction loss on wet volcanic rock at a bouldering venue where falls onto pads are routine.
Mid-August in Snowdonia often brings Atlantic frontal systems with prolonged wet spells; current conditions are typical of an unsettled period, and the 350m altitude increases exposure to low cloud and drizzle.
Contributing Factors
6
Nearly 19mm has fallen across Aug 17–19, leaving the rock surface thoroughly wet.
A further 8.3mm is forecast tomorrow (Aug 20) and 6.2mm on Aug 21, preventing any drying.
Humidity has averaged 81% over the past week with persistent cloud cover, severely inhibiting evaporation at this altitude.
The exposed hilltop setting with 15–25 km/h winds aids surface drying once rain stops.
The W/NW-facing rock receives minimal direct sun, greatly slowing drying compared to south-facing crags.
Bouldering at Caseg Fraith relies on the superb dry friction of the rhyolite, which is lost entirely when wet.
Recommendations
3
- Wait until at least Aug 23 before considering a visit, and even then assess conditions on arrival as residual dampness in sheltered areas is likely.
- If visiting later in the week, prioritise the most exposed and wind-swept boulders which will dry first, and test friction carefully before committing to harder problems.
- Monitor the forecast for Aug 23–24 closely — if the predicted dry window holds and humidity drops, afternoon sessions on Aug 23 or anytime Aug 24 may offer good conditions.
Do Not Climb
70%
63 days ago
Caseg Fraith received 7.2mm of rain today with persistent 100% cloud cover and high humidity (85–99%), leaving the rock wet and greasy. Although rain eases from mid-morning, the combination of saturated air, no sun, and a NW-facing aspect at 350m means meaningful drying is unlikely today.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Caseg Fraith's W/NW aspect receives minimal direct sun even in summer, so drying relies heavily on wind and ambient humidity — both unfavourable today with 100% cloud and humidity above 80%.
- At 350m altitude in the Ogwen Valley, the crag is frequently in or near low cloud, and today's 100% cloud cover all day suggests the rock may be enveloped in mist, keeping surfaces damp even where rain has stopped.
- The rough grit-like texture of this rhyolite provides superb friction when dry but can trap surface moisture in micro-pockets, making it deceptively slippery before it looks fully wet.
- Roadside access near the A5 makes it easy to drive up and visually assess conditions, but don't let convenience tempt you into climbing on greasy rock — the bouldering here is often above awkward landings.
Warnings
2
- Bouldering on wet rhyolite at Caseg Fraith is a serious slip hazard — the grit-like texture becomes deceptively greasy when damp, and many problems are above uneven ground.
- Significant rain is forecast for Aug 20–21 (18mm combined), so conditions will deteriorate again mid-week.
Reasoning
7.2mm of rain fell today (mostly overnight through 06:00), and with humidity remaining above 80% all day under full cloud, the rock surface is almost certainly still wet or at least damp.
Despite moderate W winds (~20–27 km/h), the complete cloud cover, high humidity (79–98%), and NW aspect mean evaporative drying is severely limited — surface moisture will linger well into the evening.
Rhyolite is non-porous and structurally unaffected by moisture; the risk is purely friction loss on wet surfaces, which is significant for bouldering with no rope.
Mid-August should offer reasonable drying conditions, but the current unsettled spell with 8.5mm in the last 7 days and a wet forecast ahead means the crag has had little chance to dry out properly.
Contributing Factors
6
7.2mm fell predominantly overnight through early morning, thoroughly wetting the rock surface.
Humidity remains 79–98% throughout the day, severely inhibiting evaporation.
100% cloud all day means zero solar heating to assist drying, especially problematic on this NW-facing crag.
Steady W winds of 19–27 km/h provide some airflow for surface drying on this exposed site.
The rock does not absorb water, so once surface moisture clears, friction returns quickly.
10mm forecast for Aug 20 and 8.2mm for Aug 21 means no extended dry window is imminent.
Recommendations
3
- Do not climb today — the rock is wet from overnight rain and conditions are not drying meaningfully under full cloud and high humidity.
- Tomorrow (Aug 19) may offer a brief window if the morning stays dry and wind picks up, but check the rock visually before committing — it could still be greasy.
- The best window this week is likely Aug 22–23 after the mid-week rain clears; drive up and assess conditions on arrival given the NW aspect's slow drying.
Marginal — Assess Conditions
55%
64 days ago
Light rain fell around midday today and humidity has been very high overnight, but the afternoon window (14:00–18:00) looks dry with moderate wind that should clear surface moisture on this exposed, non-porous rhyolite. However, the rock may still feel greasy given persistent cloud cover and high humidity, so a visual and tactile check on arrival is essential.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Caseg Fraith's W/NW aspect at 350m means it is frequently in cloud during humid SW airflows, which can deposit moisture even without measurable rain.
- The exposed position near the Ogwen Pass means wind-driven drying can be very effective, but also means low cloud and mist are common — the rock can be wet from condensation alone.
- The famous grit-like texture of the rhyolite provides exceptional friction when dry, but becomes treacherously slippery when even slightly damp; a tactile test on the rock surface is essential before committing.
- Roadside access from the A5 makes it easy to drive up, quickly assess conditions, and retreat if the rock is damp — take advantage of this.
Warnings
2
- Heavy rain is forecast for the next five days (27mm total); conditions will deteriorate significantly from tomorrow onward.
- At 350m in cloud, the rock can be wet from mist condensation even when no rain is recorded — do not assume dry weather means dry rock.
Reasoning
Light showers totalling 0.7mm fell today around 11:00–13:00 and overnight humidity exceeded 95%, so the rock surface is likely damp or has residual moisture from condensation and drizzle.
From 14:00 onward the forecast is dry with 15–16 km/h westerly winds hitting this W/NW-facing crag directly, which should strip surface moisture from the non-porous rhyolite within a couple of hours, though persistent cloud cover (69–100%) limits solar drying.
Rhyolite is non-porous and does not suffer structural weakening when wet; the only risk is friction loss from surface moisture.
Mid-August offers adequate daylight and mild temperatures, but the current unsettled spell with SW airflows is bringing repeated showers and high humidity typical of a Welsh mountain summer.
Contributing Factors
6
Around 0.6mm fell between 11:00 and 13:00, wetting the rock surface during the middle of the day.
No further precipitation is forecast from 14:00 through the evening, giving several hours of drying.
Humidity exceeded 95% overnight and remained above 80% into late morning, likely depositing condensation on the cold rock.
Moderate W/SW winds of 14–16 km/h hitting the crag directly this afternoon will accelerate surface drying on the non-porous rock.
Cloud cover remains 70–100% all day, limiting solar heating and slowing evaporation of surface moisture.
Water sits on the surface rather than being absorbed, meaning the rock dries quickly once wind and warmth increase.
Recommendations
3
- If visiting this afternoon, physically touch the rock in multiple spots — especially any sheltered or concave surfaces — before climbing; the grit-like texture can feel deceptively grippy even when slightly damp.
- Target the most wind-exposed faces and higher boulders first, as these will have dried fastest in the afternoon breeze.
- Be prepared to walk away — with heavy rain forecast from tomorrow (4.3mm+), today's afternoon window may be the last usable session for several days.
Marginal — Assess Conditions
60%
65 days ago
The rock has had a good drying spell from Aug 6–13 but recent trace precipitation today (0.4mm) and high humidity (79%) at 350m mean surfaces may carry residual dampness. With dry weather forecast only for tomorrow before a significant wet spell arrives, a visual check on arrival is warranted.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- Caseg Fraith's W/NW aspect means it receives little direct sun, so even trace moisture lingers longer than at south-facing Ogwen crags.
- At 350m the crag is frequently in cloud or mist even when valleys below are clear, which can deposit condensation on rock surfaces and reduce friction.
- The exposed position on the high pass means wind dries surface water quickly, but westerly winds can also drive rain and mist directly onto the rock face.
- Some boulder problems in sheltered gullies or north-facing alcoves may retain seepage or dampness longer than the more exposed faces.
Warnings
2
- A significant Atlantic wet spell (18mm+ over 4 days) begins Aug 18 — do not plan to climb from Tuesday through Friday.
- At 350m, cloud base may sit on the crag even on nominally dry days; if you arrive in mist, treat rock as wet regardless of the forecast.
Reasoning
Today saw 0.4mm of precipitation with 79% humidity at altitude, so rock surfaces may carry a thin film of moisture or condensation despite only trace rainfall.
The exposed position and moderate westerly winds (~13 km/h) will help evaporate surface moisture relatively quickly, but the NW aspect and high humidity slow full drying — a few hours of wind in dry air tomorrow should clear residual dampness.
Rhyolite is non-porous and not structurally weakened by moisture; the risk is purely friction loss on wet surfaces.
Mid-August in Snowdonia is peak season with generally adequate temperatures for drying, though Atlantic weather systems bring frequent showers and cloud at this altitude.
Contributing Factors
6
0.4mm of precipitation today means rock surfaces may not be fully dry, though the amount is very small.
Aug 6–13 saw zero precipitation with warm temperatures up to 29°C, ensuring deep drying of any seepage lines.
Humidity of 79% today and forecast 87% tomorrow at 350m elevation increases the chance of condensation on rock surfaces.
Consistent westerly winds around 13–18 km/h promote rapid surface evaporation on this non-porous rhyolite.
The W/NW aspect receives minimal direct sun, meaning solar drying is limited and any dampness lingers.
4.5–6.1mm daily rainfall forecast from Aug 18–20 will make conditions unsuitable from Tuesday onwards.
Recommendations
3
- Tomorrow (Aug 17) offers the best window — arrive after midday to allow any overnight condensation to clear, and touch-test rock surfaces before committing to problems.
- Avoid sheltered or north-facing boulder problems that may hold residual dampness; prioritise the most exposed, wind-scoured faces.
- Postpone any plans for Aug 18–21 as sustained heavy rain is forecast; conditions are unlikely to recover until Aug 22 at the earliest.
Climbing Outlook