Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
High for a wet and windy day Tuesday and for generally mild, unsettled and often windy conditions continuing through into the weekend, but lower for timings of arrival and clearance of more persistent bands of rain.
This evening forecast
Early clear spells but cloud soon increasing with outbreaks of rain spreading northeast towards midnight.
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.
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.
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.
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.
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.
Mountain weather forecast
Wet, especially through morning, and very windy.
| Time | 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
|
|
Chance of precipitation (at 800m) |
70% | >95% | >95% | 80% | 70% | 50% | 30% | 10% |
Wind direction and speed (mph)
Altitude above mean sea level
| Time | 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|---|---|
| 900m |
SE
35
|
S
47
|
S
58
|
S
63
|
S
66
|
SW
59
|
SW
50
|
SW
43
|
| 600m |
SE
25
|
S
36
|
S
42
|
S
47
|
S
51
|
SW
44
|
SW
36
|
SW
29
|
| 300m |
SE
17
|
S
23
|
S
26
|
S
29
|
S
32
|
SW
27
|
SW
23
|
SW
18
|
| Valley |
SE
17
|
S
23
|
S
26
|
S
28
|
S
32
|
SW
28
|
SW
23
|
SW
18
|
Wind gust (mph)
Altitude above mean sea level
| Time | 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|---|---|
| 900m | 42 | 57 | 72 | 79 | 84 | 76 | 65 | 56 |
| 600m | 32 | 46 | 56 | 62 | 69 | 60 | 50 | 42 |
| 300m | 29 | 40 | 45 | 52 | 58 | 51 | 43 | 35 |
| Valley | 30 | 40 | 45 | 50 | 57 | 50 | 41 | 35 |
Altitude above mean sea level
| Time | 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|---|---|
| 900m |
6°
|
8°
|
8°
|
9°
|
8°
|
5°
|
4°
|
4°
|
| 600m |
8°
|
9°
|
10°
|
10°
|
10°
|
8°
|
6°
|
6°
|
| 300m |
10°
|
12°
|
12°
|
12°
|
12°
|
10°
|
9°
|
8°
|
| Valley |
11°
|
12°
|
13°
|
13°
|
13°
|
12°
|
11°
|
10°
|
| Freezing Level |
2,500m
|
2,800m
|
3,100m
|
3,100m
|
2,300m
|
1,600m
|
1,400m
|
1,300m
|
Altitude above mean sea level
| Time | 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|---|---|
| 900m |
0°
|
2°
|
2°
|
2°
|
1°
|
-3°
|
-4°
|
-4°
|
| 600m |
4°
|
4°
|
5°
|
5°
|
4°
|
1°
|
0°
|
0°
|
| 300m |
7°
|
8°
|
8°
|
8°
|
7°
|
6°
|
5°
|
5°
|
| Valley |
8°
|
9°
|
9°
|
9°
|
8°
|
7°
|
7°
|
7°
|
Additional weather information
Meteorologist's view
Despite relatively mild conditions, with heavy rain and winds gusting around 90-100mph over ridges and summits there will be a significant chill effect. Warm, waterproof clothing will be essential.
Weather
Cloudy with persistent, heavy rain through the early hours. A wet start with further heavy rain, the rain turning lighter through the late morning and early afternoon, the best of any drier interludes expected across eastern hills. The rain clears from the west through the late afternoon and evening with clear spells developing. It will be very wet underfoot with swollen watercourses.
Chance of cloud-free hill tops
Little chance through the morning improving to 25%, especially in the east through the afternoon, then improving further in the evening.
Low cloud and visibility
Periods or persistent cloud above 450m to 600m, with patches below through the morning, lifting and becoming occasional at times, especially across eastern hills, to 600-750m in the afternoon, the cloud then becoming widely occasional through the evening. Away from cloud, visibility good falling to several kilometres in rain, becoming very good or excellent in the evening.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
Occasionally heavy showers and clear spells through the early hours, perhaps a little wintriness on the highest summits. Then a bright day with sunny spells and, especially through the morning, occasional showers. Dry but cloud increasing through the evening.
Chance of cloud-free hill tops
Around 40%
Maximum wind speed expected
Southwesterly 25-35mph, with gusts around 55mph over ridges and summits.
Temperature
- At 800m Around plus 5 Celsius
- Valley Around plus 7 or 8 Celsius rising to plus 10 or 11 Celsius by day
- Freezing level Above the summits
Low cloud and visibility
Occasional or periods of cloud above 600-750m. Away from cloud visibility very good or excellent, falling briefly in showers, and perhaps close to a kilometre in any early hours summit wintriness.
Mountain weather information
Thu 11 Dec
Sunrise:
Sunset:
A rather cloudy day with patchy rain and drizzle. Strong southerly or southwesterly winds with summit gales. Freezing level above the summits.
Fri 12 Dec
Sunrise:
Sunset:
Band of occasionally heavy rain pushes east overnight, soon clearing to sunny spells and occasional showers, these wintry on higher summits. Occasionally strong southerly or southwesterly winds. Freezing level falling to 1000m.
Sat 13 Dec
Sunrise:
Sunset:
Cloudy with occasionally heavy rain spreading east through morning. Strengthening southwesterly winds, risk of severe summit gales. Freezing levels soon rising above 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.