Mountain weather

Mountain weather

Eryri / Snowdonia

Confidence

High confidence for further very warm weather to end the week, though less hot compared to recently. Lower confidence regarding risk of a few showers, perhaps thundery. High confidence for a change to cooler and more changeable weather from the west this weekend, but low regarding rainfall details.

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.

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

Mostly fine and very warm, but windy at height. Small risk of a thundery shower later. Fog patches in the evening.

Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
Weather
(at 800m)
Weather symbols Sunny Sunny Sunny intervals Sunny intervals Fog Fog
Chance of
precipitation
(at 800m)
Chance of precipitation
<5%
<5%
<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 SE 35mph knots
SE
35mph
SE 17mph knots
SE
17mph
S 19mph knots
S
19mph
S 31mph knots
S
31mph
SW 37mph knots
SW
37mph
SW 32mph knots
SW
32mph
600m
600m SE 19mph knots
SE
19mph
SE 14mph knots
SE
14mph
S 18mph knots
S
18mph
S 21mph knots
S
21mph
SW 23mph knots
SW
23mph
SW 23mph knots
SW
23mph
300m
300m SE 14mph knots
SE
14mph
SE 10mph knots
SE
10mph
S 12mph knots
S
12mph
S 15mph knots
S
15mph
S 16mph knots
S
16mph
S 15mph knots
S
15mph
Valley
Valley SE 14mph knots
SE
14mph
SE 10mph knots
SE
10mph
S 12mph knots
S
12mph
S 14mph knots
S
14mph
S 16mph knots
S
16mph
S 14mph knots
S
14mph

Wind gust

Altitude above mean sea level
Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
900m 41mph 21mph 24mph 39mph 46mph 41mph
600m
600m 28mph 18mph 24mph 27mph 31mph 31mph
300m
300m 26mph 15mph 19mph 23mph 27mph 26mph
Valley
Valley 26mph 15mph 19mph 21mph 26mph 25mph

Altitude above mean sea level
Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
900m 7 degrees Celsius 11 degrees Celsius 13 degrees Celsius 9 degrees Celsius 5 degrees Celsius 4 degrees Celsius
600m
600m 12 degrees Celsius 14 degrees Celsius 15 degrees Celsius 12 degrees Celsius 8 degrees Celsius 7 degrees Celsius
300m
300m 14 degrees Celsius 18 degrees Celsius 20 degrees Celsius 16 degrees Celsius 11 degrees Celsius 10 degrees Celsius
Valley
Valley 15 degrees Celsius 20 degrees Celsius 22 degrees Celsius 17 degrees Celsius 13 degrees Celsius 12 degrees Celsius
Freezing Level Freezing Level
2700m
2600m
2700m
3000m
2700m
2100m

Additional weather information

Meteorologist's view

A risk of isolated thunderstorms during Thursday afternoon could give some hail and gusty winds. The sun is strong at this time of year, so sunscreen is advised. Fog patches are likely to impair navigation during the evening. Strong winds at higher elevations is expected to affect balance at times.

Weather

Dry, sunny and warm during the morning. Sunshine turning hazy for the afternoon, with a very slight chance of a shower breaking out, which could turn heavy and thundery. Though generally dry, cloud lowering onto hills, mainly west facing slopes, by the evening with some fog patches developing and perhaps the odd spot of drizzle. Windy at height through the day, more especially in the afternoon and early evening.

Chance of cloud-free hill tops

90% or more for the morning and away from any afternoon showers, then lowering to 40% or less in the evening.

Low cloud and visibility

The odd patch of cloud could sit on the highest hills around dawn following overnight rain, otherwise little cloud and very good visibility. Visibility dropping to moderate in any afternoon showers, then cloud lowering onto hills above about 400 or 500 metres in the evening, giving some poor or very poor visibility, though hills above 800m or so will likely lie above any cloud due to a temperature inversion.

Ground conditions

Please see - https://yrwyddfa.live/

Summit specific forecast