Mountain weather

Eryri / Snowdonia

Eryri / Snowdonia Mountain weather forecast table

Confidence

High for the overall story of rain and cloud approaching from the west through Thursday, but moderate for the precise timing of the arrival of the leading edge. High for a gradual change to more settled conditions later in the period.

Sunrise:
Sunset:

This evening forecast

Blustery showers continuing through the evening with a potential for these to be heavy at times, with some hail or thunder possible.

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 weather forecast

Drier to begin, with cloud and rain arriving from the west later.

Time 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
Weather
(at 800m)
Fog Fog Partly cloudy (night) Mist Sunny intervals Light shower (day) Fog Fog
Chance of precipitation
(at 800m)
30% 20% 10% 10% 10% 30% 60% 70%

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 SW
44
SW
44
SW
32
SW
28
SW
26
SW
26
SW
28
S
27
600m SW
31
SW
30
SW
21
SW
21
SW
21
SW
22
SW
20
S
20
300m SW
19
SW
19
SW
12
SW
14
SW
15
SW
15
S
13
S
13
Valley SW
18
SW
19
SW
11
SW
14
SW
15
SW
15
S
12
S
12
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 55 55 40 36 35 34 35 34
600m 41 40 29 29 29 30 27 27
300m 35 36 25 25 26 27 24 24
Valley 34 36 24 24 25 26 22 23

Altitude above mean sea level
Time 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m
600m
300m
10°
10°
Valley
10°
10°
11°
12°
10°
10°
Freezing Level
1,300m
1,300m
1,200m
1,300m
1,300m
1,400m
1,400m
1,600m

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

Additional weather information

Meteorologist's view

A very mixed day ahead with multiple hazards changing through the day. Initially poor visibility will be the main hazard causing navigation to become challenging. Showers through the first part of the afternoon and patchy rain and drizzle later will require waterproof layers to be worn, with warm layers also suggested due to wind chill. Improving for a time through the afternoon with view to distant hills between any showers. Deteriorating once again through the evening.

Weather

Patchy cloud likely through much of the morning period and into the afternoon, with some brighter breaks possible. This will be accompanied by a few isolated light showers, and gusty winds on the highest peaks. Cloud is expected to increase from the southwest through the afternoon bringing outbreaks of light rain and drizzle and extensive hill fog over western and southwestern facing slopes. Wet and cloudy conditions are expected to persist until after nightfall.

Chance of cloud-free hill tops

20% gradually rising to 60% for a time through the afternoon as cloud lifts, then dropping back to 20% through the afternoon as cloud and rain approaches from the west.

Low cloud and visibility

Cloud initially obstructing hills above 500m with cloud tops then dropping down to 800m allowing for the tallest peaks to clear for a time. Cloud bases are then expected to lift and become more broken at 800m through the afternoon. Through late afternoon and into the evening cloud bases are expected to drop back down to 400-600m. Outside of any cloud visibility is expected to be good or very good, with poor or very poor visibilities within cloud or showers, deteriorating further through the late afternoon and evening.

Ground conditions

Please see - https://yrwyddfa.live/

Sunrise:
Sunset:

Mountain weather information

Weather

A drier and brighter day ahead after rain and cloud gradually clears to the west. Drier and brighter thereafter with further breaks then developing through the afternoon. Potential for a light isolated shower through much of the day before dying out later. Blustery winds throughout with gale force gusts possible over the highest peaks.

Chance of cloud-free hill tops

10% gradually rising to 70% through the afternoon.

Maximum wind speed expected

Southerly or southwesterly 45-55mph

Temperature

  • At 800m Plus 5 Celsius.
  • Valley Plus 11 Celsius.
  • Freezing level Above summits.

Low cloud and visibility

Cloud initially obstructing hills above 400-500m, Cloud bases then breaking and lifting to 800-1000ft. Poor or moderate to begin especially in and cloud or light rain and drizzle. Gradually improving through the morning to very good or good outside patchy cloud or showers which could drop the visibility to poor for a brief time.

Mountain weather information

Sat 18 Apr

Sunrise:
Sunset:

A drier and brighter day ahead as high pressure begins to develop. Still the potential for patchy cloud through the day but likely above summits. Valley mist and fog early on. Freezing level above summits.

Sun 19 Apr

Sunrise:
Sunset:

A largely dry day, with light winds. Early brighter or sunny spells are likely to turn hazy as high cloud builds, however summits are likely to remain clear. Mist and fog patches to start. Freezing level staying above summits.

Mon 20 Apr

Sunrise:
Sunset:

Another fine and dry day ahead with plenty of sunny spells throughout. This will be accompanied by light winds. Freezing level staying above summits.

Updated at:

Summit specific forecast

Mountain summit forecast map

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