Mountain weather

Eryri / Snowdonia

Eryri / Snowdonia Mountain weather forecast table

Confidence

High for a ridge of high pressure holding across the area into Wednesday, but lowering for inversion height and cloud detail, then for timing of a change to a more mobile pattern into Thursday.

Sunrise:
Sunset:

This evening forecast

Gale to storm force winds bringing a widespread severe wind chill. Cloudy with some patchy light rain, falling as snow across highest peaks. Freezing level above all summits.

Sunrise:
Sunset:
Mountain hazards

Mountain weather hazards

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

hazard 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.

hazard 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.
hazard 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.

Mountain weather forecast

Most dry with occasional brighter spells. Winds strong at first.

Time 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
Weather
(at 800m)
Light rain Cloudy Partly cloudy (night) Sunny intervals Cloudy Sunny intervals Cloudy Cloudy
Chance of precipitation
(at 800m)
30% 10% <05% <05% <05% <05% <05% <05%

Wind direction and speed (mph)
Altitude above mean sea level
Time 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m E
40
E
32
E
27
E
24
E
17
E
15
E
16
E
16
600m E
22
E
19
E
17
E
18
E
16
E
12
E
12
E
12
300m E
14
E
15
E
13
E
15
E
12
E
8
E
7
E
8
Valley E
13
E
15
E
13
E
14
E
11
E
9
E
7
E
8
Wind gust (mph)
Altitude above mean sea level
Time 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m 50 41 36 35 25 21 24 23
600m 34 32 28 29 22 18 21 20
300m 27 27 24 27 21 16 15 17
Valley 25 26 23 26 19 16 14 16

Altitude above mean sea level
Time 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m
-1°
-2°
-2°
-1°
-1°
-2°
-2°
600m
300m
Valley
Freezing Level
1,600m
700m
600m
600m
600m
600m
500m
500m

Altitude above mean sea level
Time 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m
-8°
-10°
-10°
-9°
-8°
-7°
-8°
-8°
600m
-3°
-5°
-5°
-5°
-4°
-4°
-4°
-4°
300m
-2°
-2°
-2°
-1°
Valley
-1°
-1°

Additional weather information

Meteorologist's view

Gales restricted to highest peaks and before dawn. Freezing level figures above will be over simplistic at times as the inversion oscillates between 500m and 1000m.

Weather

Some patchy light rain during the early hours, perhaps wintry across highest peaks, but turning dry before dawn as a few cloud breaks appear. Most staying dry by day with brighter spells appearing most readily in the west, but the odd light outbreak of rain or drizzle may develop in the east of the Park.

Chance of cloud-free hill tops

By day 80% in west 60% in east

Low cloud and visibility

Good or very good becoming moderate in any rain or drizzle, very low within cloud which will be occasional between 500 and 900m, most frequently so in the east.

Ground conditions

Please see - https://yrwyddfa.live/

Sunrise:
Sunset:

Mountain weather information

Weather

Generally dry by day with occasional brighter spells. Cloud thickening for the evening but staying dry. Fresh to strong summit winds.

Chance of cloud-free hill tops

80% by day

Maximum wind speed expected

East or northeast mean 20-25mph with gusts reaching 40mph across most exposed ridges and summits.

Temperature

  • At 800m Minus 3 Celsius
  • Valley Plus 2 Celsius increasing 6 Celsius for the afternoon
  • Freezing level 500-600m

Low cloud and visibility

Good or very good becoming very low within cloud which will be occasional between 500m and 900m by day.

Mountain weather information

Tue 30 Dec

Sunrise:
Sunset:

Dry with brighter spells. Light summit winds. Freezing level 500-600m.

Wed 31 Dec

Sunrise:
Sunset:

Bright, dry start. Turning rather cloudy later with some chance of showers. Light summit winds. Freezing level 500-600m.

Thu 1 Jan

Sunrise:
Sunset:

Cloudy with some patchy light rain, wintry across higher peaks. Fresh to strong summit winds. Freezing level lifting to 1000m.

Updated at:

Summit specific forecast

Mountain summit forecast map

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