Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
High confidence for the ongoing unsettled weather, but low confidence with the detail with timing and extent of showers or longer spells of rain. High confidence for strong winds on Sunday and Monday.
This evening forecast
Rather windy, especially across the summits. A few showers, perhaps cloud obscuring tops above 800m but otherwise dry with clear spells.
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.
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.
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.
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.
Mountain weather forecast
Sunshine and occasional heavy showers. Strong gusty winds.
| 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) |
20% | 30% | 30% | 30% | 30% | 40% | 60% | 60% |
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 |
SW
42
|
SW
41
|
SW
40
|
S
43
|
S
44
|
S
46
|
S
44
|
S
41
|
| 600m |
SW
27
|
SW
27
|
S
28
|
S
33
|
S
35
|
S
36
|
S
33
|
S
30
|
| 300m |
SW
16
|
SW
17
|
S
17
|
S
22
|
S
24
|
S
25
|
S
22
|
S
20
|
| Valley |
SW
15
|
S
17
|
S
16
|
S
22
|
S
23
|
S
25
|
S
23
|
S
20
|
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 | 51 | 50 | 50 | 54 | 57 | 60 | 57 | 53 |
| 600m | 36 | 36 | 37 | 44 | 47 | 50 | 46 | 42 |
| 300m | 31 | 32 | 32 | 39 | 42 | 44 | 40 | 36 |
| Valley | 29 | 30 | 31 | 38 | 41 | 43 | 40 | 37 |
Altitude above mean sea level
| Time | 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|---|---|
| 900m |
8°
|
8°
|
8°
|
8°
|
9°
|
9°
|
8°
|
8°
|
| 600m |
10°
|
10°
|
10°
|
10°
|
11°
|
12°
|
11°
|
11°
|
| 300m |
13°
|
13°
|
12°
|
13°
|
14°
|
15°
|
13°
|
13°
|
| Valley |
14°
|
14°
|
14°
|
15°
|
16°
|
16°
|
15°
|
14°
|
| Freezing Level |
2,000m
|
2,000m
|
1,900m
|
1,900m
|
1,900m
|
2,100m
|
2,200m
|
2,200m
|
Altitude above mean sea level
| Time | 00:00 | 03:00 | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|---|---|
| 900m |
2°
|
2°
|
2°
|
2°
|
3°
|
3°
|
2°
|
3°
|
| 600m |
6°
|
6°
|
6°
|
6°
|
6°
|
6°
|
6°
|
6°
|
| 300m |
10°
|
10°
|
10°
|
10°
|
10°
|
10°
|
9°
|
10°
|
| Valley |
11°
|
11°
|
11°
|
11°
|
12°
|
12°
|
11°
|
11°
|
Additional weather information
Meteorologist's view
A very mixed day, with waterproofs essential, along with warm layers. Despite the sunny spells, strong winds and occasional rain could lead to it feeling nearer freezing on the summits. However, moderate UV also likely in sunny spells, so appropriate sun protection will still be needed.
Weather
A mixed day with strong winds and frequent showers moving through. These could be heavy with the odd rumble of thundery possible, and potentially merging into a more persistent period of rain later in the day. Between showers, sunny spells are likely, however it will remain rather cool on the tops due to the blustery winds.
Chance of cloud-free hill tops
70% falling to 40% during the evening
Low cloud and visibility
Cloud will occasionally obscure hills above 800m, mainly associated with heavy showers. Cloud becoming more extensive above 800m during the evening. Otherwise good visibility is expected, falling to be moderate to poor during any heavy showers.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
Another day of frequent showers, heavy and thundery at times, and occasional brighter spells. Cloud will likely be more extensive than on Sunday, with winds also lighter, but still with strong gusts. Remaining rather chilly across the summits.
Chance of cloud-free hill tops
30%
Maximum wind speed expected
Southwesterly 30-35mph gusts 40-55mph
Temperature
- At 800m Plus 8 Celsius rising to Plus 10 Celsius
- Valley Plus 12 Celsius rising to Plus 18 Celsius
- Freezing level Above summits.
Low cloud and visibility
Occasional cloud obscuring summits above 700m, with some patches possible down to 400m in any heavy showers. Good to very good visibility but falling to moderate to poor in any heavy rain.
Mountain weather information
Tue 2 Sep
Sunrise:
Sunset:
More persistent rain likely moving in through the morning, along with further strong winds. This clearing to brighter spells and showers later, although timing is low confidence.
Wed 3 Sep
Sunrise:
Sunset:
Drier start likely, with lighter winds. However further showers potentially developing through the day. Low confidence, however, with further rain possible later in the day.
Thu 4 Sep
Sunrise:
Sunset:
Unsettled conditions are expected to continue with further showers or longer spells of rain interspersed with some sunny intervals. Strong winds are also possible.
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.