Mountain weather

Eryri / Snowdonia

Eryri / Snowdonia Mountain weather forecast table

Confidence

High for an unsettled period with spells of rain and strong winds, but also some drier intervals. Also High for temperatures remaining on the mild side, with the freezing level remaining above the summits. Low confidence for rainfall details, especially from Monday onwards, and for the potential for very windy conditions on Tuesday.

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 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.
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

Frequent showers, some heavy, with low cloud. Cold and windy at height.

Time 06:00 09:00 12:00 15:00 18:00 21:00
Weather
(at 800m)
Heavy rain Hail shower (day) Heavy rain Heavy rain Light rain Overcast
Chance of precipitation
(at 800m)
70% 70% 60% 60% 70% 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
36
SW
35
SW
38
W
43
W
41
W
32
600m SW
25
SW
24
SW
27
W
31
W
28
SW
22
300m SW
16
SW
16
SW
18
W
21
W
19
SW
15
Valley SW
16
SW
16
SW
18
W
21
W
19
SW
16
Wind gust (mph)
Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m 42 42 47 53 51 40
600m 30 30 35 40 38 30
300m 27 27 32 37 34 28
Valley 27 27 31 37 34 28

Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m
600m
300m
Valley
10°
10°
10°
Freezing Level
1,400m
1,500m
1,500m
1,600m
1,600m
1,500m

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

Additional weather information

Meteorologist's view

Blustery, with gales at height, leading to a chance of being blown over. While relatively mild for December at low levels, warm waterproof layers are still essential, with the wind chill leading to it feeling sub-zero on exposed higher routes.

Weather

Mainly cloudy with frequent showers, some heavy with a small chance of hail and thunder. A few fleeting bright or clear intervals, mainly on lower slopes in the east. Rain clearing in the evening with clear spells developing.

Chance of cloud-free hill tops

20% in west, 40% in the east.

Low cloud and visibility

Frequent cloud obscuring routes above 800m, with some patches possible down to 500m in heavier showers. Away from low cloud, visibility will be good, falling to a few km at times in showers.

Ground conditions

Please see - https://yrwyddfa.live/

Sunrise:
Sunset:

Mountain weather information

Weather

Dry with clear spells overnight. Cloud and outbreaks of rain or drizzle will soon arrive from the southwest and lasting through the day, heavy at times. Rain then clearing in the evening to leave clear spells and a few mist patches.

Chance of cloud-free hill tops

60% overnight, becoming 10% for much of daylight hours, improving to 80% during the evening.

Maximum wind speed expected

Southwest 25-35mph with gusts 50mph.

Temperature

  • At 800m Plus 4 Celsius rising to Plus 7 Celsius.
  • Valley Plus 8 Celsius rising to Plus 13 Celsius.
  • Freezing level Above summits.

Low cloud and visibility

Patchy cloud above 500m at first, becoming extensive through the morning. Cloud lifting and breaking in the evening. Good visibility becoming moderate to poor by the afternoon with rain, improving again in the evening.

Mountain weather information

Mon 8 Dec

Sunrise:
Sunset:

Bright spells and showers, some heavy with a small chance of thunder. Strong southwest winds with gusts 50mph on the tops. Freezing level above summits.

Tue 9 Dec

Sunrise:
Sunset:

A wet and windy day is likely, with gales to lower levels, and a chance of storm force winds on high slopes. Freezing level well above summits.

Wed 10 Dec

Sunrise:
Sunset:

A brighter day is expected with a few showers, perhaps heavy at times. Strong southwest winds. Freezing level above summits.

Updated at:

Summit specific forecast

Mountain summit forecast map

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