Mountain weather

Mountain weather

Eryri / Snowdonia

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yellow Warning
Yellow weather warning in force for Eryri / Snowdonia

Confidence

Uncertainty remains for timings of low cloud and rain/drizzle moving northwards into the region through the afternoon, but confidence in a gradual deterioration later in the day remains high.

Sunrise: Sunset:
Sunrise: Sunset:
Mountain hazards

Mountain weather hazards

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

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.

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.

Storm Force Winds
Storm force winds (gusts over 70mph) make walking very strenuous with any mobility virtually impossible over exposed ground. Where these conditions occur there is a high risk of being blown over and even standing may be impossible at times with a risk of being blown off one’s feet. Basic tasks such as using a map, eating, putting on extra clothing or communication become extremely difficult away from any shelter.
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.
Updated: 
Mountain hazards explained

Mountain weather forecast

Mist and fog in the morning, clearer but cloudy through midday with rain/drizzle starting. Mist/fog returning later. Feeling gusty on western summits.

Time
 Time
06:00
09:00
12:00
15:00
18:00
21:00
Weather
(at 800m)
 Weather symbols Fog Fog Fog Drizzle Drizzle Drizzle
Chance of
precipitation
(at 800m)
 Chance of precipitation
10%
10%
20%
40%
40%
70%

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 E 26mph knots
E
26mph
 E 26mph knots
E
26mph
 E 26mph knots
E
26mph
 E 24mph knots
E
24mph
 E 28mph knots
E
28mph
 E 30mph knots
E
30mph
600m
 600m SE 18mph knots
SE
18mph
 SE 17mph knots
SE
17mph
 SE 17mph knots
SE
17mph
 E 13mph knots
E
13mph
 E 16mph knots
E
16mph
 E 16mph knots
E
16mph
300m
 300m SE 14mph knots
SE
14mph
 SE 14mph knots
SE
14mph
 SE 15mph knots
SE
15mph
 E 11mph knots
E
11mph
 E 12mph knots
E
12mph
 E 13mph knots
E
13mph
Valley
 Valley SE 14mph knots
SE
14mph
 SE 14mph knots
SE
14mph
 SE 15mph knots
SE
15mph
 E 10mph knots
E
10mph
 E 11mph knots
E
11mph
 E 12mph knots
E
12mph

Wind gust

Altitude above mean sea level
Time
 Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
 900m 36mph 36mph 35mph 32mph 39mph 42mph
600m
 600m 28mph 28mph 27mph 24mph 28mph 29mph
300m
 300m 29mph 27mph 26mph 21mph 25mph 26mph
Valley
 Valley 29mph 27mph 26mph 20mph 24mph 24mph

Altitude above mean sea level
Time
 Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
 900m -6 degrees Celsius -6 degrees Celsius -6 degrees Celsius -5 degrees Celsius -5 degrees Celsius -5 degrees Celsius
600m
 600m 1 degrees Celsius 0 degrees Celsius 0 degrees Celsius 1 degrees Celsius 0 degrees Celsius 0 degrees Celsius
300m
 300m 1 degrees Celsius 1 degrees Celsius 3 degrees Celsius 4 degrees Celsius 3 degrees Celsius 3 degrees Celsius
Valley
 Valley 2 degrees Celsius 2 degrees Celsius 4 degrees Celsius 6 degrees Celsius 5 degrees Celsius 5 degrees Celsius
Freezing Level Freezing Level
1200m
1200m
1200m
1400m
1700m
1700m

Additional weather information

Meteorologist's view

A potentially misty and foggy start, especially on eastern hills, will give way to improved visibility for a time from midday before rain and drizzle moves in from the south. By evening, mist and fog will have returned with persistent rain and drizzle so good navigation skills will again be required. Wind will feel gusty on western slopes throughout the day, especially on exposed summits or ridges, with noticeable buffeting of clothes likely and balance affected. Cold temperatures at height mixed with incoming wet conditions will bring a risk of severe wind chill so suitable clothing as advised.

Weather

Largely dry to start, perhaps with hazy sunshine possible on highest ground in the west, but with otherwise extensive mist and hill fog over eastern slopes and some western summits. Visibility will improve for a time into late morning and through early afternoon before rain and drizzle moves in from the south, affecting most summits by sunset. This will increase in intensity into the evening with mist and hill fog returning to high ground. Western summits and ridges will feel gusty at times with a risk of severe wind chill.

Chance of cloud-free hill tops

Small chance of highest peaks standing clear of cloud throughout. Otherwise more generally 20% around sunrise, increasing to 60% by early afternoon particularly on western hills before reducing to 20% again into the evening.

Low cloud and visibility

Extensive very poor visibility in the east especially in low cloud and valley mist and fog. A cloud layer is likely to persist above 500 metres throughout, although good visibility is possible over the highest ground in the west.

Ground conditions

No recent ground conditions report available.

Summit specific forecast

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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