Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
High for generally mild and occasionally unsettled weather. Lowering confidence for the timing detail of the worst of the conditions.
Mountain weather hazards
Hazards apply at or above 300m, reflecting the more severe conditions which can occur at altitude.
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.
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.
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.
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.
Mountain weather forecast
Mostly fair by day. Rain developing into evening. Summit gales.
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
Chance of precipitation (at 800m) |
<05% | <05% | <05% | <05% | 20% | 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 |
S
55
|
S
49
|
S
45
|
S
42
|
S
44
|
S
40
|
| 600m |
S
38
|
S
32
|
S
32
|
S
29
|
S
31
|
S
29
|
| 300m |
S
23
|
S
21
|
S
21
|
S
20
|
S
21
|
S
19
|
| Valley |
S
23
|
S
21
|
S
21
|
S
21
|
S
21
|
S
19
|
Wind gust (mph)
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m | 65 | 60 | 55 | 52 | 54 | 49 |
| 600m | 47 | 42 | 41 | 38 | 40 | 38 |
| 300m | 39 | 36 | 36 | 34 | 36 | 33 |
| Valley | 39 | 36 | 36 | 35 | 37 | 33 |
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
3°
|
3°
|
4°
|
4°
|
4°
|
4°
|
| 600m |
6°
|
6°
|
6°
|
7°
|
7°
|
7°
|
| 300m |
8°
|
8°
|
9°
|
10°
|
9°
|
9°
|
| Valley |
10°
|
10°
|
10°
|
11°
|
11°
|
10°
|
| Freezing Level |
1,200m
|
1,300m
|
1,400m
|
1,500m
|
1,600m
|
1,700m
|
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
-6°
|
-5°
|
-3°
|
-3°
|
-3°
|
-3°
|
| 600m |
-1°
|
-1°
|
1°
|
2°
|
1°
|
1°
|
| 300m |
4°
|
4°
|
5°
|
6°
|
5°
|
6°
|
| Valley |
6°
|
6°
|
7°
|
7°
|
7°
|
7°
|
Additional weather information
Meteorologist's view
Risk of storm force winds confined to the highest routes.
Weather
Most staying dry through the day with some limited bright spells, but the odd light, isolated shower may appear. Cloud thickening from the west into the evening bringing patchy rain, which turns heavier and more persistent towards midnight.
Chance of cloud-free hill tops
70% by day, becoming 10% by midnight.
Low cloud and visibility
Good or very good becoming moderate or poor in rain or showers, very poor within cloud which occasionally lowers to 800m by day, then 600m late evening.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
Small chance of some early rain around dawn. Otherwise a largely dry and bright morning, before occasional showers developing for the afternoon and evening. Summit winds increasing strong from mid-day, bringing a severe wind chill at height.
Chance of cloud-free hill tops
40% at dawn, otherwise 80% by day
Maximum wind speed expected
Southwest increasing mean 25-30mph from noon, with gusts reaching 35-40mph across exposed ridges and summits
Temperature
- At 800m Plus 3 Celsius
- Valley Plus 5 Celsius increasing 10 Celsius for the afternoon
- Freezing level Above summits
Low cloud and visibility
Good or very good becoming moderate or poor in any early rain or later showers, very poor within cloud, with a small chance quite extensive at 800m around dawn, but lifted and well broken for the rest of the day.
Mountain weather information
Sat 13 Dec
Sunrise:
Sunset:
Cloud and rain soon spreading from the west, the rain becoming persistent and heavy, with storm force summit winds developing. Freezing level above all summits.
Sun 14 Dec
Sunrise:
Sunset:
Rain, heavy and persistent through much of the day, may clear to more showery conditions later. Gale to severe gale summit winds. Freezing level above all summits.
Mon 15 Dec
Sunrise:
Sunset:
Chance of a further period of rain, perhaps heavy, but confidence low for detail. Severe gale to storm force summit winds possible. Freezing level above all summits.
Updated at:
Summit specific forecast
Mountain summit forecast map
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Key
Mountain summits
Other points of interest
Cluster of multiple stations
The Eryri (Snowdonia) mountains are made up of 90 mountain peaks including the tallest mountain in Wales, Yr Wyddfa (Snowdon), standing at 1,085 metres.