Mountain weather

Eryri / Snowdonia

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Eryri / Snowdonia Mountain weather forecast table

Confidence

Medium confidence in details of the forecast however timing of clearance of mist and fog on Wednesday morning is more uncertain. Stormy conditions expected on Friday so keep a close eye on the forecast to keep up to date with the latest information.

Sunrise:
Sunset:

This evening forecast

Outbreaks of light rain and drizzle, further south dry with mist and fog patches forming during the evening, light southerly winds.

Sunrise:
Sunset:
Mountain hazards

Mountain weather hazards

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

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.

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.
Mountain hazards explained

Mountain weather forecast

Early mist and fog clearing, sunny spells and light winds for the rest of the day.

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
Weather
(at 800m)
 Mist Fog Fog Mist Sunny intervals Sunny intervals Mist Fog
Chance of precipitation
(at 800m)
 10% 10% 10% 10% 10% 10% 10% 10%

Wind direction and speed (mph)
Altitude above mean sea level
00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m S
6
 S
5
 SW
4
 SW
4
 W
6
 W
8
 W
10
 SW
12
600m S
7
 S
6
 SE
4
 S
5
 SW
5
 W
6
 W
6
 SW
9
300m S
4
 S
4
 SE
3
 SE
3
 W
3
 W
3
 SW
3
 SW
4
Valley S
4
 S
4
 SE
3
 S
4
 SW
3
 W
3
 SW
3
 S
5
Wind gust (mph)
Altitude above mean sea level
00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m 7 6 5 6 9 11 11 15
600m 9 7 5 7 7 8 8 12
300m 7 6 4 5 5 6 5 9
Valley 7 6 5 5 5 6 5 10

Altitude above mean sea level
00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m
0°
0°
0°
0°
0°
0°
-1°
-1°
600m
2°
2°
2°
2°
2°
2°
1°
1°
300m
4°
4°
3°
3°
4°
4°
3°
2°
Valley
5°
4°
4°
4°
5°
6°
4°
4°
Freezing Level
1,000m
900m
900m
800m
800m
800m
800m
800m

Altitude above mean sea level
00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m
-3°
-2°
-3°
-3°
-3°
-4°
-6°
-6°
600m
-1°
-1°
-1°
-1°
0°
-1°
-2°
-3°
300m
2°
2°
2°
2°
3°
3°
1°
0°
Valley
3°
3°
3°
2°
4°
4°
3°
1°

Additional weather information

Meteorologist's view

Very light winds but freezing level lowering to 800m so feeling cooler later.

Weather

Mist and fog will form overnight and may take some time to clear in the morning, otherwise a bright day with some sunny intervals. Mist and fog are likely to form again in the late afternoon and evening period.

Chance of cloud-free hill tops

40% improving to 80% later, low cloud may be slow to clear around western mountains.

Low cloud and visibility

Scattered or broken low cloud above 400m at the start of the day in the west, this will slowly lift and clear but patches or periods of low cloud can be expected for much of the day above 600m around western hills. Clear summits and views are more likely for the south and eastern mountains. Visibility will be poor or very poor initially in mist and fog but becoming very good for the main part of the day.

Ground conditions

Please see - https://yrwyddfa.live/

Sunrise:
Sunset:

Mountain weather information

Weather

Precipitation soon spreading east over Snowdonia on Thursday morning, falling as sleet or snow above 800m by late morning as freezing level falls in the afternoon. Some sunny spells developing during the afternoon and clear spells in the evening.

Chance of cloud-free hill tops

20% improving to 80%, low cloud in association with precipitation spreading east.

Maximum wind speed expected

South 25 mph with gusts 35-40mph.

Temperature

  • At 800m Zero Celsius.
  • Valley Plus 2 Celsius rising to 5 Celsius.
  • Freezing level 800m

Low cloud and visibility

Layers of broken cloud above 400m and thickening during the morning, especially around western mountains, perhaps more cloud breaks further south and east towards Bala. Moderate visibility in the morning with some morning mist likely, visibility will be poor at times in rainfall at lower levels and very poor in sleet or snow on the higher mountains, accompanied by strong winds, blizzard conditions are a possibility on the highest tops.

Mountain weather information

Fri 24 Jan

Sunrise:
Sunset:

Storm Eowyn is forecast to cross the United Kingdom with some heavy rain initially and severe gales expected for North Wales. A few brighter spells in the afternoon but gales likely to continue. Freezing level rising above all summits in the morning but falling to 400m in the afternoon.

Sat 25 Jan

Sunrise:
Sunset:

Feeling very cold but a bright day with some sunny spells, Fresh or strong southwesterly winds continuing. Freezing level around 400m.

Sun 26 Jan

Sunrise:
Sunset:

A bright start but some outbreaks of rain expected and light winds initially but chance of further strong winds or gales later.

Updated at:
Mountain weather explained

Summit specific forecast

Mountain summit forecast map

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The Eryri (Snowdonia) mountains are made up of 90 mountain peaks including the tallest mountain in Wales, Yr Wyddfa (Snowdon), standing at 1,085 metres.

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