Mountain weather

Eryri / Snowdonia

Eryri / Snowdonia Mountain weather forecast table

Confidence

High confidence for an unsettled and changeable period of weather. Lower for rain or snow detail so please keep updated on the forecast.

Sunrise:
Sunset:

This evening forecast

Dry with clear spells. Fresh westerly winds with a severe wind chill on the tops. Freezing level 800m.

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.

hazard Blizzards
Blizzards and whiteouts present challenging and serious conditions due to a combination of falling or blowing snow, strong winds and cold temperatures. They can be highly disorientating, often resulting in near-zero visibility with limited or no visual references and no distinction between ground and sky. Cliff edges and cornices may not be apparent, even close up. These conditions require very good navigational skills.
hazard Heavy Persistent Snow
Heavy snow can lead to rapid changes in underfoot conditions and paths may become treacherous or hidden. It also brings very poor visibility and often makes navigation much more challenging. When deep snow accumulates progress is often time consuming and strenuous, significantly affecting the distance one can travel on foot. Deep drifts can develop if snow is combined with strong winds. A heightened avalanche risk is possible and avalanche reports should be consulted where available.
hazard 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.
hazard Thunderstorms
Lightning is a significant mountain hazard which can result in serious injury or death. Mountain terrain often leaves one highly exposed to lightning strikes. Hail may give unpleasant conditions with torrential rain and localised flash flooding also possible, mainly in Summer months.

Mountain weather forecast

Mostly dry morning. Rain, sleet and summit snow arriving with very strong winds in afternoon.

Time 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
Weather
(at 800m)
Light snow shower (night) Light snow shower (night) Fog Sunny intervals Cloudy Heavy snow Sleet Heavy rain
Chance of precipitation
(at 800m)
30% 30% 20% 10% 10% >95% >95% >95%

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
23
SW
23
S
21
S
30
S
47
SE
48
S
49
S
37
600m SW
15
S
15
S
16
S
23
S
34
SE
36
SE
36
S
26
300m SW
9
S
9
S
10
S
15
S
23
SE
26
SE
26
S
17
Valley SW
9
S
10
S
10
S
15
S
24
SE
27
SE
27
S
16
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 28 28 25 36 57 61 63 48
600m 20 20 20 30 44 49 49 36
300m 18 18 18 27 40 44 44 31
Valley 18 19 19 28 40 45 46 30

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
Valley
Freezing Level
800m
1,000m
1,000m
1,000m
1,000m
1,200m
1,600m
1,500m

Altitude above mean sea level
Time 00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m
-7°
-6°
-6°
-7°
-8°
-9°
-8°
-4°
600m
-3°
-2°
-2°
-3°
-4°
-5°
-4°
300m
-1°
Valley

Additional weather information

Meteorologist's view

A window of fair conditions at first but note the quick deterioration in the afternoon. A severe wind chill developing with walking becoming very difficult or possibly dangerous on higher slopes and ridges in the severe gales or storm force winds.

Weather

Clear spells and a few showers in the early hours, wintry above 600m. A mainly dry morning with some bright spells then rain will spread northeast from early afternoon, heavy at times with severe gale or storm force winds. There will be a couple of hours of sleet or snow above 600m, before turning to rain at all levels by evening. Heavy showers following in the evening, perhaps thundery.

Chance of cloud-free hill tops

70%, becoming 10% during the afternoon.

Low cloud and visibility

Patchy cloud above 500m at first, this lifting in the morning with mostly good visibility for a few hours. However, conditions deteriorate rapidly in the afternoon with extensive cloud developing giving poor visibility above 500m.

Ground conditions

Please see - https://yrwyddfa.live/

Sunrise:
Sunset:

Mountain weather information

Weather

A mixture of clear or bright intervals and rain showers, heavy at times with a small chance of thunder.

Chance of cloud-free hill tops

30%.

Maximum wind speed expected

Southwest 20-30mph gusts 40mph.

Temperature

  • At 800m Plus 1C to 3C.
  • Valley Plus 7 to 9C.
  • Freezing level Above summits.

Low cloud and visibility

Areas of cloud with bases 500 to 700m giving periods of very poor visibility. Good visibility on lower slopes but occasionally few km in showers.

Mountain weather information

Sun 7 Dec

Sunrise:
Sunset:

A band of rain is expected to move east in the morning accompanied by strong winds. Drier and brighter conditions following. Freezing level above summits, falling to 1000m in afternoon.

Mon 8 Dec

Sunrise:
Sunset:

This is likely to be a mostly bright day with possibly a few sharp showers. Strong to gale force southerly winds on the tops. Wet, stormy conditions perhaps arriving in evening. Freezing level 1000m rising above summits.

Tue 9 Dec

Sunrise:
Sunset:

A lot of uncertainty by this stage but a spell of wet and very windy conditions is likely followed by brighter weather from the southwest. Mild with freezing level above summits.

Updated at:

Summit specific forecast

Mountain summit forecast map

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