Mountain weather

Eryri / Snowdonia

Yellow warning

Yellow weather warning in force for Eryri / Snowdonia

Eryri / Snowdonia Mountain weather forecast table

Confidence

High initially, reducing later into the week.

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 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 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 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

Very wet with persistent heavy rain and gale to severe gale force south-westerly winds.

Time 06:00 09:00 12:00 15:00 18:00 21:00
Weather
(at 800m)
Heavy rain Heavy rain Heavy rain Heavy rain Heavy rain Sleet shower (night)
Chance of precipitation
(at 800m)
>95% >95% >95% 90% 80% 70%

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
46
SW
51
SW
44
SW
39
SW
37
SW
33
600m SW
31
S
36
SW
29
SW
28
SW
26
SW
23
300m SW
17
S
20
SW
17
SW
17
SW
16
SW
15
Valley SW
17
S
20
SW
18
SW
17
SW
16
SW
15
Wind gust (mph)
Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m 54 60 54 48 45 41
600m 37 44 38 36 34 30
300m 31 36 33 31 31 27
Valley 31 36 34 31 30 27

Altitude above mean sea level
Time 06:00 09:00 12:00 15:00 18:00 21:00
900m
600m
300m
11°
11°
10°
10°
Valley
12°
12°
12°
11°
10°
Freezing Level
2,400m
2,300m
2,100m
2,000m
1,600m
1,300m

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

Additional weather information

Meteorologist's view

A Met Office Yellow NSWWS warning for rain has been issued for the area through Monday, with heavy rain likely to bring some disruption. Some very poor navigational and underfoot conditions likely out on the hills and care should be taken.

Weather

Dull with persistent heavy rain, strong winds and extensive hill fog through much of the day. Watercourses will be fast flowing and flooding may well impact some access roads and parking areas. Rain turning showery late evening, still heavy at times with the low risk of a rumble of thunder and rain turning increasingly to sleet or snow above 900m.

Chance of cloud-free hill tops

<10% through daylight hours. Increasing to 40% into the evening.

Low cloud and visibility

Persistent cloud above 400-500m through daylight hours, with occasional bases to 200-300m in the west. Some lifting and breaking of cloud bases above summits into the late afternoon and evening. Visibility often poor due to heavy rain, and very poor at height.

Ground conditions

Please see - https://yrwyddfa.live/

Sunrise:
Sunset:

Mountain weather information

Weather

Bright or sunny intervals and a few showers in the morning then cloudier in the afternoon with more frequent showers, some heavy with the chance of thunder, and falling as snow above 900m.

Chance of cloud-free hill tops

60% in morning falling 30% in afternoon.

Maximum wind speed expected

Southwesterly 30 gusts 40mph.

Temperature

  • At 800m Plus 1 Celsius.
  • Valley Plus 7 Celsius.
  • Freezing level 1000m.

Low cloud and visibility

Broken or occasional cloud at 600-900m in morning becoming more extensive in afternoon with the odd patch to 500m. Visibility good away from cloud and showers falling moderate to poor in the showers, and very poor in hill fog above the cloud line.

Mountain weather information

Wed 3 Dec

Sunrise:
Sunset:

A few bright or sunny intervals, but mostly cloudy, with a few showers, snow above 1000m, and some summit hill fog. Fresh to strong south to southwest winds.

Thu 4 Dec

Sunrise:
Sunset:

Cloudy with heavy rain and hill fog in the morning with strong southerly winds, then brighter afternoon with sunshine breaking through and easing southwesterly winds. Freezing level above summits falling 800m later.

Fri 5 Dec

Sunrise:
Sunset:

A dry morning with sunny spells and patchy valley fog. Becoming cloudier in afternoon then rain and strong winds in the evening, freezing levels rising from 700m to above summits.

Updated at:

Summit specific forecast

Mountain summit forecast map

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