Climbing Forecast › Snowdonia — Nantlle › Cwm Silyn

SNOWDONIA — NANTLLE · RHYOLITE

Cwm Silyn climbing conditions

Poor — wet, too windy or closed

Right now

Temp18°C
Wind15 km/h
Gusts18 km/h
Humidity96.98%
Rain 48h0mm
Last rainNone recent

Assessment

0.3mm rain forecast
Humidity 87% — potential fog

7-day forecast

Scroll through each day — hourly detail is shown inline.

Today Friday 14 August
Poor
Temp19°C
Rain0.3mm
Wind13 km/h
Gusts23 km/h
Humidity87%
0.3mm rain forecastHumidity 87% — potential fog
  • Damp mountain air — upper pitches may stay greasy
Time °C Rain Wind Gust Hum
06:00 18° 0mm 15 18 96.98%
09:00 19° 0mm 9 12 87.27%
12:00 19° 0.28mm 10 14 95.78%
15:00 18° 0mm 16 23 78.15%
18:00 18° 0mm 16 23 70.49%
21:00 17° 0mm 9 16 82.96%
Sat Saturday 15 August
Good
Temp17°C
Rain0mm
Wind18 km/h
Gusts28 km/h
Humidity59%
Should be dry
Time °C Rain Wind Gust Hum
06:00 14° 0.03mm 12 21 91.42%
09:00 15° 0mm 19 28 72.51%
12:00 16° 0mm 19 28 61.36%
15:00 17° 0mm 18 28 56.74%
18:00 17° 0mm 15 25 59.11%
21:00 15° 0mm 8 14 72.48%
Sun Sunday 16 August
Good
Temp17°C
Rain0mm
Wind12 km/h
Gusts25 km/h
Humidity61%
Should be dry
Time °C Rain Wind Gust Hum
06:00 13° 0mm 5 8 82.22%
09:00 15° 0mm 7 16 69.17%
12:00 17° 0mm 11 24 61.2%
15:00 18° 0mm 13 25 61.14%
18:00 17° 0mm 11 20 65.68%
21:00 16° 0mm 9 14 84.34%
Mon Monday 17 August
Poor
Temp18°C
Rain1mm
Wind17 km/h
Gusts30 km/h
Humidity76%
1mm rain forecast
  • Wet rhyolite is slippery; seepage from grass above can linger
Time °C Rain Wind Gust Hum
06:00 15° 0mm 11 17 92.53%
09:00 16° 0.29mm 15 25 83.84%
12:00 18° 0mm 17 29 76.67%
15:00 19° 0mm 17 30 74.57%
18:00 18° 0mm 19 31 81.57%
21:00 17° 0.71mm 19 31 92.71%
Tue Tuesday 18 August
Poor
Temp18°C
Rain6mm
Wind21 km/h
Gusts38 km/h
Humidity79%
6mm rain forecast
  • Wet rhyolite is slippery; seepage from grass above can linger
  • Breezy — helps drying
Time °C Rain Wind Gust Hum
06:00 17° 0.87mm 22 34 95.1%
09:00 17° 1.19mm 22 37 91.58%
12:00 17° 1.02mm 22 38 82.2%
15:00 18° 0.55mm 20 35 76.45%
18:00 18° 0mm 19 30 77.13%
21:00 17° 0.42mm 19 28 86.68%
Wed Wednesday 19 August
Poor
Temp16°C
Rain1.3mm
Wind24 km/h
Gusts41 km/h
Humidity65%
1.3mm rain forecast
  • Good temperature for mountain rhyolite
  • Wet rhyolite is slippery; seepage from grass above can linger
  • Breezy — helps drying
Time °C Rain Wind Gust Hum
06:00 14° 0.35mm 23 34 87.38%
09:00 15° 0.33mm 25 40 76.01%
12:00 16° 0mm 25 41 66.9%
15:00 17° 0mm 23 39 62.52%
18:00 17° 0mm 20 32 68.19%
21:00 16° 0.31mm 20 30 83.08%
Thu Thursday 20 August
Poor
Temp16°C
Rain2.8mm
Wind21 km/h
Gusts39 km/h
Humidity68%
2.8mm rain forecast
  • Good temperature for mountain rhyolite
  • Wet rhyolite is slippery; seepage from grass above can linger
  • Breezy — helps drying
Time °C Rain Wind Gust Hum
06:00 13° 0.49mm 21 31 89.33%
09:00 14° 0.58mm 23 37 78.61%
12:00 16° 0.62mm 22 39 69.84%
15:00 16° 0.6mm 21 36 66.54%
18:00 16° 0mm 19 30 69.86%
21:00 15° 0mm 16 24 83.84%
Fri Friday 21 August
Caution
Temp13°C
Rain0mm
Wind16 km/h
Gusts—
Humidity—
Should be dryHigh seepage — may still be weeping
  • Good temperature for mountain rhyolite
Cwm Silyn consists of two impressive mountain buttresses, Craig yr Cwm Silyn, rising above a high corrie in the western Pennant hills. The rock is high-quality volcanic ash, offering clean slabs, sharp ribs, and featured crack lines on sound mountain rock. Facing northwest, the crag receives sun only in late afternoon, resulting in cold conditions and persistent dampness in sheltered cracks. Climbing centers on classic lower and middle-grade traditional multi-pitch routes, headlined by Kirkus' Route and Outside Edge. The approach demands a forty-five minute uphill walk across rough moorland and boulder fields from the Nantlle valley. Because of its remote, shaded mountain aspect, rapid weather changes and lingering dampness are the primary considerations.

About Cwm Silyn

Cwm Silyn consists of two impressive mountain buttresses, Craig yr Cwm Silyn, rising above a high corrie in the western Pennant hills. The rock is high-quality volcanic ash, offering clean slabs, sharp ribs, and featured crack lines on sound mountain rock. Facing northwest, the crag receives sun only in late afternoon, resulting in cold conditions and persistent dampness in sheltered cracks. Climbing centers on classic lower and middle-grade traditional multi-pitch routes, headlined by Kirkus' Route and Outside Edge. The approach demands a forty-five minute uphill walk across rough moorland and boulder fields from the Nantlle valley. Because of its remote, shaded mountain aspect, rapid weather changes and lingering dampness are the primary considerations.

Region
Snowdonia — Nantlle
Rock type
rhyolite
Aspect
north-west-facing
Altitude
550m
Exposure
high
Seepage
high

Other crags in this region

Craig y Bera