Mountain weather

Eryri / Snowdonia

Eryri / Snowdonia Mountain weather forecast table

Confidence

Medium

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 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 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 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

Variable cloud and scattered showers. Windy, summit gales.

Time 06:00 09:00 12:00 15:00 18:00 21:00
Weather
(at 800m)
Sunny intervals Light shower (day) Light shower (day) Sunny intervals Partly cloudy (night) Partly cloudy (night)
Chance of precipitation
(at 800m)
30% 40% 60% 30% 20% 20%

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
45
SW
37
SW
39
SW
37
SW
37
SW
37
600m SW
30
SW
26
SW
28
SW
27
SW
25
SW
24
300m SW
19
SW
16
S
18
SW
17
SW
16
SW
16
Valley SW
19
SW
16
S
18
SW
17
SW
16
SW
16
Wind gust (mph)
Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m 54 46 48 47 46 46
600m 37 33 36 36 33 33
300m 33 29 31 30 30 30
Valley 33 29 31 29 29 29

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

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

Additional weather information

Meteorologist's view

Nothing further to add.

Weather

Variable cloud with a few bright spells and scattered showers, which will perhaps merge in a longer spells of rain for a time in around midday, which could be heavy. Windy with summit gales at times along with a significant wind chill.

Chance of cloud-free hill tops

30% to the west of the park, around 50% in the east

Low cloud and visibility

Broken or extensive cloud, base widespread around 600-900 metres to the west of the park, with more in the way of breaks further east, bases occasionally falling to 300 to 600m in and around any showers. Visibility mostly good or very good, but moderate to very poor in cloud and rain.

Ground conditions

Please see - https://yrwyddfa.live/

Sunrise:
Sunset:

Mountain weather information

Weather

Outbreaks of heavy rain overnight and during the morning, perhaps wintry over the highest summits. Becoming dry with the cloud lifting and breaking during the afternoon with clear spells in the evening, a touch of frost expected.

Chance of cloud-free hill tops

30% becoming 70% in the afternoon.

Maximum wind speed expected

Southwest 25 to 30mph turning Northwest 10 to 15mph, significant wind chill at first.

Temperature

  • At 800m Plus 2 Celsius falling Minus 1 Celsius later
  • Valley Plus 4 to 7 Celsius, falling 1 Celsius in the evening.
  • Freezing level Above the summits falling 600m or less later

Low cloud and visibility

Occasional or extensive low cloud, base 300 to 600m, lifting and breaking near or above the summit through the afternoon. Visibility often moderate to very poor at first, becoming mostly very good later.

Mountain weather information

Wed 14 Jan

Sunrise:
Sunset:

Mainly dry and bright with a frost possible at first. Outbreaks of rain and snow in the evening. Strengthening southerly winds later. Freezing most or all levels at first, gradually rising towards the summits.

Thu 15 Jan

Sunrise:
Sunset:

Outbreaks of rain and snow soon clearing to wintry showers. Freezing level typically around the summits, but 400 to 600m late in the period. Winds moderate to fresh from the southwest.

Fri 16 Jan

Sunrise:
Sunset:

A dry and bright or clear start. Wintry showers developing during the day. Freezing level below the summits. Light or moderate southeast becoming northeast winds.

Updated at:

Summit specific forecast

Mountain summit forecast map

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