Mountain weather

Mountain weather

Eryri / Snowdonia

Confidence

High overall. Low to moderate for possible thunderstorms.

Mountain hazards

Mountain weather hazards

Hazards apply at or above 300m, reflecting the more severe conditions which can occur at altitude.

Strong Sunlight
Harmful UV levels from sunlight increase with altitude giving a greater risk of sunburn and eye damage, even on some overcast days. On breezy days, the cooling effect of wind on exposed skin may disguise any feeling of sunburn until it is too late. If there is snow cover, glare increases the effect of UV rays especially on the eyes. It is advisable to wear sun block, protective clothing such as a long-sleeved top and hat and have good quality eye protection.

Gales
Gale force winds (gusts over 50mph) make walking difficult and strenuous with a potential to be blown over by gusts. There is often a marked increase in winds through cols or on exposed ridges and summits. Distances can take longer to cover and compass bearings become harder to follow accurately.
Poor Visibility
Poor visibility presents challenging route finding conditions. Visibility could be significantly less than 50 metres in all directions with few or no visual references, especially on featureless moors or plateaux. Distances become hard to judge and cliff or cornice edges can be difficult to recognise. These conditions require good navigational skills. There is a risk of white-out conditions when mist or fog is combined with extensive snow cover.
Thunderstorms
Lightning is a significant mountain hazard which can result in serious injury or death. Mountain terrain often leaves one highly exposed to lightning strikes. Hail may give unpleasant conditions with torrential rain and localised flash flooding also possible, mainly in Summer months.

Mountain weather forecast

Low cloud clearing quickly to plenty of blue skies and very warm sunshine.

Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
Weather
(at 800m)
Weather symbols Sunny intervals Sunny Sunny Sunny Sunny Clear night
Chance of
precipitation
(at 800m)
Chance of precipitation
10%
10%
<5%
10%
10%
10%

Wind direction and speed

Altitude above mean sea level
Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
900m E 35mph knots
E
35mph
E 37mph knots
E
37mph
E 28mph knots
E
28mph
E 23mph knots
E
23mph
E 27mph knots
E
27mph
E 34mph knots
E
34mph
600m
600m E 23mph knots
E
23mph
E 23mph knots
E
23mph
E 21mph knots
E
21mph
E 17mph knots
E
17mph
E 16mph knots
E
16mph
E 20mph knots
E
20mph
300m
300m E 16mph knots
E
16mph
E 14mph knots
E
14mph
E 14mph knots
E
14mph
E 12mph knots
E
12mph
E 11mph knots
E
11mph
E 14mph knots
E
14mph
Valley
Valley E 16mph knots
E
16mph
E 14mph knots
E
14mph
E 14mph knots
E
14mph
E 12mph knots
E
12mph
E 11mph knots
E
11mph
E 14mph knots
E
14mph

Wind gust

Altitude above mean sea level
Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
900m 43mph 44mph 36mph 30mph 34mph 45mph
600m
600m 35mph 32mph 29mph 22mph 22mph 33mph
300m
300m 31mph 27mph 24mph 20mph 21mph 30mph
Valley
Valley 31mph 27mph 24mph 20mph 21mph 29mph

Altitude above mean sea level
Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
900m 7 degrees Celsius 8 degrees Celsius 12 degrees Celsius 14 degrees Celsius 12 degrees Celsius 9 degrees Celsius
600m
600m 11 degrees Celsius 12 degrees Celsius 15 degrees Celsius 19 degrees Celsius 18 degrees Celsius 13 degrees Celsius
300m
300m 14 degrees Celsius 17 degrees Celsius 21 degrees Celsius 23 degrees Celsius 22 degrees Celsius 16 degrees Celsius
Valley
Valley 15 degrees Celsius 18 degrees Celsius 22 degrees Celsius 25 degrees Celsius 24 degrees Celsius 18 degrees Celsius
Freezing Level Freezing Level
3000m
3100m
3100m
3200m
3300m
3100m

Additional weather information

Meteorologist's view

A brilliant day to be in the national park, however sun protection application and re-application is advised due to very high UV levels. Additionally, the high temperatures may exhaust individuals, especially in the afternoon. Frequent rehydration and taking regular breaks from strenuous activities is advisable. A hat and eye protection should also be considered.

Weather

Some patchy low cloud likely pushing in from the east through the overnight period, mainly effecting the east of the park. This should quickly clear soon after dawn to leave a dry and bright day with lengthy spells of sunshine and a brisk easterly breeze.

Chance of cloud-free hill tops

70%, quickly rising to >95%.

Low cloud and visibility

Patchy cloud bases around 400-600m, quickly lifting and dissipating to leave cloud free summits. Low cloud, mainly to the east of the park, may limit visibilities briefly around dawn on the highest peaks. This will quickly clear away to leave excellent visibilities with views of distant peaks possible.

Ground conditions

Please see - https://yrwyddfa.live/

Summit specific forecast