Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
High for Wednesday, and for a generally unsettled rest of the week. Some uncertainty in the position of heavy rain and strength of winds on Thursday, and for position of rain bands over the weekend.
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.
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.
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
Rain soon turning heavy and persistent. Severe summit gales.
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
Chance of precipitation (at 800m) |
20% | 70% | 70% | >95% | >95% | 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
59
|
S
60
|
S
56
|
S
59
|
S
54
|
W
22
|
| 600m |
S
41
|
S
40
|
S
39
|
S
40
|
S
34
|
SW
15
|
| 300m |
S
27
|
S
25
|
S
26
|
S
26
|
S
21
|
W
7
|
| Valley |
S
27
|
S
26
|
S
26
|
S
26
|
S
21
|
W
7
|
Wind gust (mph)
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m | 69 | 70 | 67 | 71 | 64 | 28 |
| 600m | 49 | 48 | 50 | 51 | 44 | 21 |
| 300m | 44 | 42 | 44 | 45 | 38 | 17 |
| Valley | 44 | 42 | 44 | 45 | 38 | 16 |
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
1°
|
2°
|
4°
|
4°
|
6°
|
5°
|
| 600m |
3°
|
4°
|
6°
|
6°
|
7°
|
6°
|
| 300m |
5°
|
6°
|
7°
|
8°
|
9°
|
8°
|
| Valley |
6°
|
7°
|
8°
|
9°
|
10°
|
9°
|
| Freezing Level |
1,200m
|
2,500m
|
2,600m
|
2,600m
|
2,400m
|
2,200m
|
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
-8°
|
-7°
|
-5°
|
-4°
|
-2°
|
0°
|
| 600m |
-5°
|
-3°
|
-1°
|
0°
|
2°
|
3°
|
| 300m |
0°
|
1°
|
2°
|
3°
|
5°
|
6°
|
| Valley |
1°
|
2°
|
4°
|
5°
|
7°
|
7°
|
Additional weather information
Meteorologist's view
Gusts of 70-75 mph likely over the higher summits from mid-morning. Heavy rain will result in very wet underfoot conditions with high watercourses making any river crossings hazardous. Some flooding of footpaths and access roads is possible.
Weather
Outbreaks of rain spreading in from the west. Rain turns heavier in the afternoon and much of the evening with gales, occasionally storm force winds over the summits. Turning largely dry around midnight.
Chance of cloud-free hill tops
Nil.
Low cloud and visibility
Very poor visibility with cloud down to 500m in the early hours, lower slopes through the day. Some cloud breaks towards midnight.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
Low cloudy through the early hours and morning, some patchy drizzle, but largely dry. Outbreaks of occasionally heavy rain spreads north later in the morning, clearing around early evening. Turning largely dry with clear spells late evening, a few isolated showers possible.
Chance of cloud-free hill tops
Becoming 60% by afternoon, 10% by late evening.
Maximum wind speed expected
Southerly 25-30 gusting 40 mph increasing to 35-40 gusting 50 mph at time from late morning and through the afternoon. Winds becoming Southwest in the evening.
Temperature
- At 800m Plus 4 or 5 Celsius, falling to plus 1 Celsius late evening.
- Valley Plus 7 Celsius rising to 9 Celsius.
- Freezing level Above the summits, falling to 800-900m late evening.
Low cloud and visibility
Very poor visibility with cloud extensive to lower slopes for much of the day, although cloud may lift to around 600-800m at times. Hills becoming cloud free in the evening.
Mountain weather information
Fri 19 Dec
Sunrise:
Sunset:
Bright and breezy with a few well scattered showers. Cloud increasing later in the day. Strong southwest winds, feeling colder than recent days, although freezing level 1000m, rising to just above the summits.
Sat 20 Dec
Sunrise:
Sunset:
After a dry cloudy start rain will turn persistent and occasionally heavy. Strong south or southwest winds with summit gales likely. Freezing level above the summits.
Sun 21 Dec
Sunrise:
Sunset:
A generally cloudy day with hill fog and outbreaks of rain at times. Moderate generally south or southeast winds. Freezing level remaining above the 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.