Mountain weather

Mountain weather

Eryri / Snowdonia

Confidence

High for a showery day on Wednesday. Wet and windy on Thursday. Low for the chance of any thunderstorms.

Mountain hazards

Mountain weather hazards

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

Severe Chill Effect
Wind significantly lowers the ‘feels-like’ temperature relative to the actual temperature, with even moderate winds significantly adding to the chilling effect. Strong winds can result in a severe and debilitating wind chill many degrees below the actual temperature. This effect will be enhanced in rain or wet snow. Without protection, prolonged exposure could result in frost nip or frostbite on exposed parts of the body and/or hypothermia.
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.
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.

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

Sunshine and showers. Heavy and possibly thundery.

Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
Weather
(at 800m)
Weather symbols Heavy rain showers Heavy rain showers Light rain showers Sunny intervals Sunny intervals Partly cloudy (night)
Chance of
precipitation
(at 800m)
Chance of precipitation
60%
60%
60%
30%
30%
20%

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 W 19mph knots
W
19mph
W 19mph knots
W
19mph
W 19mph knots
W
19mph
W 22mph knots
W
22mph
W 17mph knots
W
17mph
W 15mph knots
W
15mph
600m
600m W 13mph knots
W
13mph
W 16mph knots
W
16mph
W 15mph knots
W
15mph
W 17mph knots
W
17mph
W 14mph knots
W
14mph
SW 10mph knots
SW
10mph
300m
300m W 8mph knots
W
8mph
W 10mph knots
W
10mph
W 11mph knots
W
11mph
W 12mph knots
W
12mph
W 10mph knots
W
10mph
SW 5mph knots
SW
5mph
Valley
Valley W 8mph knots
W
8mph
W 10mph knots
W
10mph
W 11mph knots
W
11mph
W 12mph knots
W
12mph
W 10mph knots
W
10mph
SW 5mph knots
SW
5mph

Wind gust

Altitude above mean sea level
Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
900m 23mph 24mph 25mph 28mph 22mph 18mph
600m
600m 16mph 20mph 21mph 23mph 18mph 13mph
300m
300m 14mph 16mph 19mph 21mph 16mph 12mph
Valley
Valley 14mph 16mph 18mph 21mph 16mph 12mph

Altitude above mean sea level
Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
900m -2 degrees Celsius -2 degrees Celsius -1 degrees Celsius 0 degrees Celsius 1 degrees Celsius 1 degrees Celsius
600m
600m 2 degrees Celsius 2 degrees Celsius 3 degrees Celsius 4 degrees Celsius 4 degrees Celsius 5 degrees Celsius
300m
300m 6 degrees Celsius 6 degrees Celsius 7 degrees Celsius 8 degrees Celsius 8 degrees Celsius 8 degrees Celsius
Valley
Valley 8 degrees Celsius 8 degrees Celsius 9 degrees Celsius 10 degrees Celsius 10 degrees Celsius 10 degrees Celsius
Freezing Level Freezing Level
1300m
1400m
1400m
1500m
1500m
1600m

Additional weather information

Meteorologist's view

Conditions could change quickly throughout the day so keep waterproofs on hand. Also remember that UV levels will be high when the sunshine does emerge, despite the brisk wind making it feel chilly.

Weather

Showers from the start, these will be heavy and possibly thundery, with the risk of hail. Some drier and brighter interludes in between the showers. Showers becoming less frequent into the afternoon, with more in the way of sunny spells and easing by the evening. Breezy and gusty around heavy downpours. Feeling cool.

Chance of cloud-free hill tops

30% rising to 80%.

Low cloud and visibility

Patches of low cloud from mid-morning around 400-600 m, lifting and rising mostly above summits to by the afternoon. Moderate visibility to start but rising to good, dropping in any heavy downpours.

Ground conditions

Please see - https://yrwyddfa.live/

Summit specific forecast