Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
High for unsettled main theme and rising temperatures, but notably low for detail given very weak progression of inbound weather systems.
This evening forecast
Temperatures falling sharply during the evening as skies clear, with valley fog potentially hampering late descents. Local sharp visibility deteriorations and icy patches are also expected given isolated light showers drfiting in from the north.
Mountain weather hazards
Hazards apply at or above 300m, reflecting the more severe conditions which can occur at altitude.
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.
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.
Mountain weather forecast
Friday fine for a time after fog and frost, isolated wintry showers developing later.
| 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
|
|
Chance of precipitation (at 800m) |
00% | 10% | 20% | 10% | 30% | 40% | 20% | 20% |
Wind direction and speed (mph)
Altitude above mean sea level
| 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|---|---|
| 900m |
NE
14
|
E
14
|
E
14
|
E
14
|
NE
10
|
NE
12
|
NE
15
|
NE
16
|
| 600m |
E
9
|
E
10
|
E
10
|
E
11
|
NE
9
|
NE
11
|
NE
11
|
E
11
|
| 300m |
E
5
|
E
7
|
E
6
|
E
8
|
NE
7
|
NE
10
|
NE
9
|
E
8
|
| Valley |
E
5
|
E
6
|
E
5
|
E
8
|
NE
8
|
NE
12
|
NE
9
|
E
7
|
Wind gust (mph)
Altitude above mean sea level
| 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|---|---|
| 900m | 18 | 17 | 18 | 20 | 15 | 17 | 21 | 23 |
| 600m | 13 | 15 | 15 | 17 | 14 | 17 | 17 | 18 |
| 300m | 11 | 13 | 13 | 15 | 14 | 17 | 16 | 16 |
| Valley | 11 | 13 | 12 | 14 | 15 | 20 | 16 | 14 |
Altitude above mean sea level
| 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|---|---|
| 900m |
-1°
|
-2°
|
-2°
|
0°
|
1°
|
2°
|
1°
|
-1°
|
| 600m |
1°
|
0°
|
1°
|
2°
|
4°
|
4°
|
3°
|
2°
|
| 300m |
3°
|
2°
|
3°
|
5°
|
7°
|
6°
|
6°
|
4°
|
| Valley |
5°
|
4°
|
4°
|
6°
|
8°
|
8°
|
7°
|
6°
|
| Freezing Level |
700m
|
600m
|
500m
|
500m
|
600m
|
700m
|
700m
|
800m
|
Altitude above mean sea level
| 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|---|---|
| 900m |
-6°
|
-8°
|
-8°
|
-6°
|
-3°
|
-3°
|
-5°
|
-6°
|
| 600m |
-2°
|
-4°
|
-4°
|
-2°
|
1°
|
0°
|
-1°
|
-2°
|
| 300m |
1°
|
-1°
|
0°
|
2°
|
4°
|
4°
|
3°
|
1°
|
| Valley |
3°
|
1°
|
2°
|
4°
|
5°
|
4°
|
4°
|
3°
|
Additional weather information
Meteorologist's view
The UV index will be moderate, and lower than average temperatures coupled with the breeze may render the Sun's stregth deceptive.
Weather
Cold with clear periods during the early hours, with a hard frost in valleys and some freezing fog patches developing locally. Fine into daybreak, with local fog dispersing and some hazy sunny spells developing for a time. Fair weather cloud will build into the afternoon to the extent of producing a few snow showers above around 500 metres, with these mostly light but perhaps the odd heavier one in the east. Becoming drier but cloudier into the evening, with temperatures again falling sharply.
Chance of cloud-free hill tops
40 improving 90% by mid-morning.
Low cloud and visibility
Visibility generally very good, but notable deteriorations in snow showers and some locally poor visibility in valleys first thing.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
Low confidence relative to the period. Probably a fine start with the best of any limited hazy sunshine in the north as cloud and rain stall at a distance to the south, although note high uncertainty. Probably tending to become cloudier with time, and with an attendant risk of some showery rain and summit snow later on.
Chance of cloud-free hill tops
30%
Maximum wind speed expected
Northeasterly 30mph easing.
Temperature
- At 800m Zero becoming plus 2 Celsius.
- Valley Minus 2 becoming plus 11 Celsius.
- Freezing level Sub-zero in valleys at first, else 800 metres rising to around the highest ground.
Low cloud and visibility
Good visibility in the main, but broken cloud probably persisting around 800 metres.
Mountain weather information
Sun 28 Apr
Sunrise:
Sunset:
Note relatively low confidence in details through this three-day period. Sunday perhaps fine but cloudy, as persistent and occasionally heavy rain probably passes remote from the east of the Park. Light and variable, perhaps downslope winds early on, increasing moderate southwesterly later. Freezing level around the highest ground and rising.
Mon 29 Apr
Sunrise:
Sunset:
Probably a brighter day, but with strong winds and a chance of rain later. Strong southwest, later southerly winds. Freezing level clear of all summits.
Tue 30 Apr
Sunrise:
Sunset:
Becoming more unsettled again, with showers or longer spells of rain arriving on a moderate southeasterly wind. Freezing level clear of all 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.