Mountain weather

Eryri / Snowdonia

Eryri / Snowdonia Mountain weather forecast table

Confidence

High for the mobile nature of the westerly weather patterns through Tuesday then for high pressure extending from the northeast thereafter, but lowering for the transitional timing detail.

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 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 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 Heavy Persistent Rain
Heavy and persistent rain can lead to drenched clothing and footwear with waterproofs often becoming soaked through, especially if accompanied by strong winds. This can lead to significant loss of body heat and an increased likelihood of hypothermia. Terrain may turn increasingly boggy underfoot while streams can flood and become impassable. There may also be a risk of flooding in valleys or glens. If there is snow cover, a heightened avalanche hazard is possible and avalanche reports should be consulted where available.

Mountain weather forecast

Showers merging to longer periods of rain from late morning. Strong to gale winds.

Time 06:00 09:00 12:00 15:00 18:00 21:00
Weather
(at 800m)
Cloudy Cloudy Light rain Heavy rain Light rain Light rain
Chance of precipitation
(at 800m)
20% 20% 60% 70% 60% 60%

Wind direction and speed (mph)
Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m W
34
W
34
SW
32
SW
41
SW
42
SW
40
600m SW
21
SW
24
SW
24
SW
28
SW
27
SW
25
300m SW
13
W
15
SW
17
SW
18
SW
18
SW
17
Valley SW
13
W
15
SW
16
SW
18
SW
18
SW
17
Wind gust (mph)
Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m 40 42 40 50 51 49
600m 27 31 32 37 36 34
300m 24 27 29 31 33 31
Valley 24 26 28 32 33 31

Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m
-1°
600m
300m
Valley
Freezing Level
700m
900m
1,100m
2,100m
2,000m
1,800m

Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m
-10°
-8°
-6°
-4°
-4°
-3°
600m
-5°
-4°
-1°
300m
Valley

Additional weather information

Meteorologist's view

Potentially hazardous conditions in extensive hill fog, driving rain and a severe wind chill at height late morning through to late afternoon. Gales across more exposed ridges and summits.

Weather

Beginning with limited brighter spells and perhaps some isolated showers, these wintry above 500-600m. Cloud thickening from the west to bring periods of rain from late morning, turning heavier early to mid-afternoon, before becoming patchy and light for the late afternoon and evening.

Chance of cloud-free hill tops

60% initially becoming 10% or less from mid-day

Low cloud and visibility

Good or very good becoming moderate or poor in rain and showers, very poor in early snow showers and within cloud, which becomes extensive from 500m from late morning

Ground conditions

Please see - https://yrwyddfa.live/

Sunrise:
Sunset:

Mountain weather information

Weather

Mainly cloudy with some patchy light rain and summit gales. Freezing level above summits.

Chance of cloud-free hill tops

10-20%

Maximum wind speed expected

South or southwest mean 30-40mph, with gusts reaching 60mph across more exposed ridges and summits.

Temperature

  • At 800m Plus 4 Celsius
  • Valley Plus 8 Celsius increasing 14 Celsius for the afternoon
  • Freezing level Above summits

Low cloud and visibility

Good or very good becoming moderate or poor in rain, very poor within cloud, which will be quite extensive from 500m.

Mountain weather information

Wed 18 Mar

Sunrise:
Sunset:

Dry with brighter spells increasing into the afternoon. Fresh to strong easterly summit winds developing late in day. Freezing level above summits.

Thu 19 Mar

Sunrise:
Sunset:

Dry with bright and sunny spells. Fresh easterly summit winds. Freezing level above summits.

Fri 20 Mar

Sunrise:
Sunset:

Dry with good sunny spells. Light winds. Freezing level above summits.

Updated at:

Summit specific forecast

Mountain summit forecast map

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