Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
High for unsettled and changeable conditions during this period with potential for stormy conditions on Tuesday. Lower confidence for wind and rain details from Tuesday.
Mountain weather hazards
Hazards apply at or above 300m, reflecting the more severe conditions which can occur at altitude.
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.
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.
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
Wet and windy with low cloud during the day.
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
Chance of precipitation (at 800m) |
30% | 90% | >95% | >95% | 60% | 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 |
SE
25
|
SE
30
|
S
37
|
SW
48
|
W
41
|
SW
36
|
| 600m |
S
20
|
S
23
|
SE
26
|
SW
32
|
W
29
|
SW
24
|
| 300m |
SE
12
|
SE
16
|
SE
18
|
SW
21
|
W
19
|
SW
15
|
| Valley |
SE
12
|
SE
16
|
SE
18
|
SW
21
|
W
19
|
SW
15
|
Wind gust (mph)
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m | 29 | 35 | 44 | 58 | 51 | 45 |
| 600m | 26 | 29 | 32 | 42 | 37 | 32 |
| 300m | 22 | 28 | 31 | 36 | 33 | 28 |
| Valley | 22 | 28 | 32 | 36 | 34 | 29 |
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
5°
|
6°
|
7°
|
8°
|
4°
|
4°
|
| 600m |
7°
|
8°
|
9°
|
9°
|
6°
|
6°
|
| 300m |
8°
|
10°
|
11°
|
11°
|
8°
|
8°
|
| Valley |
9°
|
11°
|
12°
|
12°
|
10°
|
9°
|
| Freezing Level |
2,300m
|
2,200m
|
2,700m
|
2,300m
|
1,600m
|
1,400m
|
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
0°
|
1°
|
2°
|
2°
|
-3°
|
-3°
|
| 600m |
3°
|
4°
|
5°
|
5°
|
1°
|
1°
|
| 300m |
6°
|
7°
|
8°
|
7°
|
5°
|
5°
|
| Valley |
7°
|
8°
|
9°
|
8°
|
6°
|
6°
|
Additional weather information
Meteorologist's view
Gusts of 50 to 60mph above 600m for a time in the afternoon. Difficult and potentially dangerous conditions on high exposed ridges and summits with slippery surfaces and a chance of being blown off balance.
Weather
A wet day with spells of rain or drizzle, turning heavy at times into the afternoon. Rain clearing soon after dark then clear spells and a few showers in the evening. Strong winds developing with summit gales in the afternoon and evening.
Chance of cloud-free hill tops
Nil chance for much of the day, but improving to perhaps 70% during the evening.
Low cloud and visibility
Patchy low cloud on the tops becoming extensive and lowering into the morning. Cloud and fog extensive above 300 or 400m for most of the day bringing difficult navigation conditions. Cloud slowly lifting after dark but continuing to affect higher summits.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
Showers moving east during the early morning, some heavy with a small chance of hail and thunder. Otherwise largely dry with clear or sunny spells by day but remaining breezy. More persistent rain and stronger winds spreading north during the evening.
Chance of cloud-free hill tops
50% becoming 90%.
Maximum wind speed expected
South or Southwest 20 to 30mph with gusts 40 to 50mph.
Temperature
- At 800m Plus 4 or 5C.
- Valley Plus 8C rising to 11C.
- Freezing level Above summits.
Low cloud and visibility
Patchy cloud to 500 or 600m during the morning as showers move through, lifting above summits into the day. Mostly good visibility.
Mountain weather information
Tue 9 Dec
Sunrise:
Sunset:
Very windy conditions with storm force winds likely for a time. A period of heavy rain in the morning followed by bright spells and showers. Freezing level above summits.
Wed 10 Dec
Sunrise:
Sunset:
Bright spells and showers. Very strong and gusty westerly winds with severe gales at height. Freezing level above summits.
Thu 11 Dec
Sunrise:
Sunset:
A window of drier and brighter weather with lighter winds is possible. Low confidence.
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.