Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
High for unsettled, often wintry conditions throughout the forecast period, including a period of very strong winds on Thursday. Lower for the snow-level on Friday, and the timings of arrival and clearance of more persistent bands of rain and snow, especially by 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.
Blizzards
Blizzards and whiteouts present challenging and serious conditions due to a combination of falling or blowing snow, strong winds and cold temperatures. They can be highly disorientating, often resulting in near-zero visibility with limited or no visual references and no distinction between ground and sky. Cliff edges and cornices may not be apparent, even close up. These conditions require very good navigational skills.
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.
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
Very windy with heavy rain spreading south. Snow on summits after dark.
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
Chance of precipitation (at 800m) |
40% | 50% | 90% | 90% | 90% | 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 |
SW
61
|
SW
58
|
SW
60
|
SW
61
|
SW
50
|
SW
41
|
| 600m |
SW
42
|
S
42
|
SW
45
|
SW
46
|
SW
35
|
SW
28
|
| 300m |
S
25
|
S
25
|
SW
25
|
SW
26
|
SW
21
|
SW
16
|
| Valley |
S
26
|
S
26
|
SW
26
|
SW
26
|
SW
20
|
SW
14
|
Wind gust (mph)
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m | 73 | 71 | 74 | 75 | 63 | 52 |
| 600m | 52 | 54 | 58 | 59 | 47 | 37 |
| 300m | 44 | 45 | 46 | 47 | 40 | 30 |
| Valley | 44 | 46 | 47 | 47 | 37 | 27 |
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
3°
|
4°
|
6°
|
6°
|
4°
|
1°
|
| 600m |
5°
|
6°
|
7°
|
7°
|
6°
|
4°
|
| 300m |
7°
|
8°
|
9°
|
9°
|
8°
|
6°
|
| Valley |
8°
|
9°
|
10°
|
10°
|
9°
|
7°
|
| Freezing Level |
1,400m
|
1,800m
|
1,900m
|
1,900m
|
1,500m
|
1,000m
|
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
-7°
|
-4°
|
-2°
|
-2°
|
-4°
|
-7°
|
| 600m |
-3°
|
-1°
|
1°
|
1°
|
-1°
|
-3°
|
| 300m |
2°
|
3°
|
4°
|
5°
|
4°
|
2°
|
| Valley |
4°
|
5°
|
6°
|
6°
|
5°
|
4°
|
Additional weather information
Meteorologist's view
Winds will become very hazardous across the higher routes and summits, with the potential to blow people off their feet. Gusts are likely to exceed 90mph over high routes such as Crib Goch. Even for lower level walks progress is likely to be impeded times, with sudden gusts likely, especially during the afternoon. Warm waterproof layers essential.
Weather
A cloudy morning with outbreaks of rain turning persistent, and then briefly heavier later in the afternoon. Winds also strengthening throughout, becoming very strong and gusty for time. Rain will then ease during the evening, but further showers following. The snow level falling also after dark to be around 400m by midnight.
Chance of cloud-free hill tops
Little chance in west by day, but improving to 20% after dark. 25% throughout in the east.
Low cloud and visibility
Cloud obscuring hills above 500m in the west, but more occasional and obscuring routes above 750m clear in the east. Some patches possible down to 400m during heaviest rain during the afternoon. Outside of cloud, visibility will be good falling to several kilometres in rain and drizzle. Improving to be very good after dark, but very poor in any snowfall, with near blizzard conditions on the summits.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
Cold, with tops and high level routes likely icy after Thursdays rain. Sunny spells and isolated showers expected, these falling as snow above 300m during the morning, before this snow level gradually rises to around 600m by the late afternoon. Showers becoming more likely through the evening, perhaps brief blizzard conditions on the highest tops. Still breezy, with a notable chill, although not as windy as Thursday.
Chance of cloud-free hill tops
80% falling to 30% during the evening.
Maximum wind speed expected
Southwesterly 30-35mph gusting 40-50mph.
Temperature
- At 800m Minus 2 Celsius rising Zero Celsius
- Valley Plus 4 Celsius rising to Plus 7 Celsius
- Freezing level 450m rising to 800m through the late afternoon.
Low cloud and visibility
Cloud largely above summit level, though the odd patch could obscure routes above 600m during the day. An area of more widespread cloud then moves in from the north through the evening, widely obscure routes above 500m, with the odd patch down to 400m. Some southern and eastern hills remaining clearer, with cloud more broken. Outside of cloud, visibility will be very good falling to around 5-10 kilometres in heavy rain, and a kilometre or so in any snow, perhaps lower on summits with the strong winds bringing near blizzard conditions.
Mountain weather information
Sat 14 Mar
Sunrise:
Sunset:
A few early wintry showers then mainly dry with sunny spells. Cloud increasing through the evening. Occasionally strong westerly winds backing southwesterly and easing. Freezing level around 800m.
Sun 15 Mar
Sunrise:
Sunset:
Cloudy with rain, preceded by snow on higher summits, clearing to sunny spells and blustery wintry showers in afternoon. Windy with summit gales. Freezing level above summits, falling to 600m later.
Mon 16 Mar
Sunrise:
Sunset:
Early wintry showers dying out with sunny spells developing but cloud and rain spreading east in afternoon. Strong westerly winds, summit gales, easing. Freezing level 600m, rising later.
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.