Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
High for the mobile nature of the westerly weather pattern, but lowering for the transitional timing detail.
Mountain weather hazards
Hazards apply at or above 300m, reflecting the more severe conditions which can occur at altitude.
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.
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.
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.
Strong Sunlight
Harmful UV levels from sunlight increase with altitude giving a greater risk of sunburn and eye damage, even on some overcast days. On breezy days, the cooling effect of wind on exposed skin may disguise any feeling of sunburn until it is too late. If there is snow cover, glare increases the effect of UV rays especially on the eyes. It is advisable to wear sun block, protective clothing such as a long-sleeved top and hat and have good quality eye protection.
Mountain weather forecast
Wintry showers, turning heavy at times, with strong winds. Severe chill effect.
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
Chance of precipitation (at 800m) |
20% | 60% | 70% | 70% | 30% | 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 |
W
30
|
NW
31
|
NW
29
|
NW
26
|
NW
27
|
NW
28
|
| 600m |
W
20
|
NW
22
|
NW
22
|
NW
20
|
W
16
|
W
15
|
| 300m |
W
13
|
NW
16
|
NW
17
|
NW
15
|
NW
10
|
NW
9
|
| Valley |
W
13
|
NW
16
|
NW
17
|
NW
15
|
NW
10
|
W
9
|
Wind gust (mph)
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m | 36 | 39 | 38 | 33 | 33 | 34 |
| 600m | 25 | 30 | 30 | 28 | 21 | 21 |
| 300m | 22 | 27 | 28 | 25 | 18 | 19 |
| Valley | 22 | 27 | 29 | 25 | 19 | 19 |
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
-3°
|
-2°
|
-1°
|
-1°
|
-1°
|
-1°
|
| 600m |
0°
|
0°
|
2°
|
2°
|
2°
|
2°
|
| 300m |
2°
|
3°
|
4°
|
5°
|
4°
|
4°
|
| Valley |
4°
|
5°
|
6°
|
6°
|
6°
|
5°
|
| Freezing Level |
500m
|
500m
|
500m
|
600m
|
600m
|
700m
|
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
-12°
|
-11°
|
-10°
|
-8°
|
-9°
|
-9°
|
| 600m |
-7°
|
-7°
|
-5°
|
-4°
|
-4°
|
-4°
|
| 300m |
-2°
|
-2°
|
0°
|
0°
|
0°
|
1°
|
| Valley |
0°
|
0°
|
2°
|
2°
|
2°
|
2°
|
Additional weather information
Meteorologist's view
Severe wind chill above 300m, increasing to become very significant severe chill over the summits.
Weather
Showers of snow, sleet and rain, frequent from mid-morning to mid-afternoon. The showers will be heavy at times with the risk of hail and thunder. The showers will become lighter and less frequent from late-afternoon.
Chance of cloud-free hill tops
80% becoming 40% by mid-morning, then 80% from late-afternoon.
Low cloud and visibility
Distant hills clearly visible but deteriorating to poor or very poor with showers and within cloud. Occasional bases 800m with showers, perhaps temporarily decreasing 600-700m with heaviest showers.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
Dry but becoming cloudy overnight. Rain, often heavy, then arriving by mid-morning, with snow initially across highest routes. Rain clears southwards mid to late afternoon, with broken cloud and scattered showers following. These turn heavier and wintry across highest routes late evening. Gale to severe gale summit winds developing.
Chance of cloud-free hill tops
80% at dawn becoming 10% or less mid-morning, then 60% by early evening.
Maximum wind speed expected
West or southwest increasing by mid-day to mean 50mph with gusts reaching 65mph across exposed ridges and summits.
Temperature
- At 800m Plus 0 Celsius increasing 5 Celsius for the afternoon
- Valley Plus 3 Celsius increasing 12 Celsius for the afternoon
- Freezing level 700m increasing above the summits then falling to 1000m later.
Low cloud and visibility
Distant hills clearly visible then decreasing to near-by hills with rain, and poor or very poor in snow and within cloud. Bases becoming extensive from 500-600m from mid-morning, before lifting and breaking later.
Mountain weather information
Mon 30 Mar
Sunrise:
Sunset:
Often cloudy with a few light showers. Becoming cloudy later with patchy light rain and hill fog arriving. Gale to severe gale winds gradually easing. Freezing level 1000m lifting above the summits soon.
Tue 31 Mar
Sunrise:
Sunset:
Beginning cloudy with patchy light rain and hill fog, then turning largely dry and occasionally bright for the afternoon. Fresh to strong winds. Freezing level above the summits.
Wed 1 Apr
Sunrise:
Sunset:
Cloudy with occasional light rain. Widespread hill fog likely. Fresh to strong winds. Freezing level 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.