Mountain weather

Eryri / Snowdonia

Eryri / Snowdonia Mountain weather forecast table

Confidence

High confidence in the unsettled and often very windy conditions prevailing during the next few days, but with a much brighter day on Friday after a wet Thursday.

Sunrise:
Sunset:
Mountain hazards

Mountain weather hazards

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

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 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 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

A mainly dry start, but rain arriving late morning, occasionally heavy. Risk of gales on summits and ridges.

Time 06:00 09:00 12:00 15:00 18:00 21:00
Weather
(at 800m)
Mist Heavy rain Heavy rain Light rain Heavy shower (night) Light shower (night)
Chance of precipitation
(at 800m)
10% 20% 80% 80% 40% 30%

Wind direction and speed (mph)
Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m SW
25
S
37
S
35
S
34
SW
37
W
35
600m S
16
S
26
S
25
S
23
SW
27
W
23
300m S
9
S
18
S
16
S
14
SW
16
W
14
Valley S
9
S
18
S
16
S
14
SW
16
W
15
Wind gust (mph)
Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m 29 43 42 41 45 43
600m 20 32 31 29 35 31
300m 18 30 27 25 30 27
Valley 18 30 27 24 30 27

Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m
600m
300m
Valley
Freezing Level
1,000m
1,200m
1,400m
1,500m
1,400m
900m

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

Additional weather information

Meteorologist's view

Strong winds and summit gales will give a notable wind chill at height, this enhanced by the wet afternoon conditions. High watercourses will make river crossings hazardous, perhaps impassable.

Weather

A mainly dry morning with just a few patches of hill fog. Rain arrives by late morning, occasionally heavy so making for drenching conditions for a time into the afternoon. Rain then clears late aftenoon to leave scattered showers for the evening. Occasional strong winds at height and a risk of gales on summits and ridges.

Chance of cloud-free hill tops

40% decreasing to 20% in afternoon.

Low cloud and visibility

Patches of cloud on higher upslopes in the morning with generally good visibility otherwise. Visibility then deteriorating to a couple of kilometres or less in rain, with cloud bases thickening and lowering to 400m at times.

Ground conditions

Please see - https://yrwyddfa.live/

Sunrise:
Sunset:

Mountain weather information

Weather

A bright and very blustery day with sunny intervals. Dry for some but passing showers likely, some may be heavy with hail.

Chance of cloud-free hill tops

80%

Maximum wind speed expected

Gusting 40-50mph at height.

Temperature

  • At 800m Plus 2 Celsius.
  • Valley Plus 3 rising 8 Celsius.
  • Freezing level 1000m

Low cloud and visibility

Patches of cloud down to around 700m in any showers, otherwise mainly clear with good visibility.

Mountain weather information

Sat 20 Dec

Sunrise:
Sunset:

Strong winds, with gales or severe gales at height. A dry and bright start but turning cloudier with outbreaks of rain. Freezing level 1200m.

Sun 21 Dec

Sunrise:
Sunset:

Fairly cloudy with a few outbreaks of rain. Freezing level 1000m. Moderate to fresh summit winds.

Mon 22 Dec

Sunrise:
Sunset:

Remaining rather cloudy with a risk of a few spells of light rain. Fresh to strong summit winds and freezing level well above summits.

Updated at:

Summit specific forecast

Mountain summit forecast map

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