Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
Low for detail throughout, particularly showers and prevalance and clearance of poor visibility.
Mountain weather hazards
Hazards apply at or above 300m, reflecting the more severe conditions which can occur at altitude.
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.
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
Murky and damp, very gradually becoming drier and brighter, but probably staying cloudy throughout.
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
Chance of precipitation (at 800m) |
20% | 10% | 30% | 30% | 20% | 10% |
Wind direction and speed (mph)
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
SE
7
|
SW
5
|
W
6
|
NW
8
|
NW
6
|
N
3
|
| 600m |
S
7
|
SW
6
|
NW
6
|
NW
8
|
NW
6
|
N
3
|
| 300m |
S
3
|
W
4
|
NW
4
|
NW
7
|
NW
5
|
NW
2
|
| Valley |
S
3
|
W
4
|
NW
5
|
NW
7
|
NW
5
|
W
2
|
Wind gust (mph)
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m | 8 | 7 | 9 | 11 | 9 | 4 |
| 600m | 9 | 9 | 9 | 11 | 9 | 4 |
| 300m | 6 | 6 | 7 | 10 | 7 | 3 |
| Valley | 6 | 7 | 8 | 11 | 7 | 4 |
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
8°
|
9°
|
10°
|
10°
|
10°
|
10°
|
| 600m |
10°
|
10°
|
12°
|
12°
|
12°
|
12°
|
| 300m |
12°
|
13°
|
14°
|
14°
|
14°
|
12°
|
| Valley |
13°
|
14°
|
15°
|
15°
|
15°
|
12°
|
| Freezing Level |
2,400m
|
2,300m
|
2,300m
|
2,300m
|
2,300m
|
2,300m
|
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
6°
|
8°
|
9°
|
8°
|
9°
|
10°
|
| 600m |
8°
|
9°
|
11°
|
10°
|
11°
|
11°
|
| 300m |
11°
|
12°
|
14°
|
13°
|
14°
|
12°
|
| Valley |
12°
|
14°
|
15°
|
14°
|
14°
|
12°
|
Additional weather information
Meteorologist's view
Wind directions are likely to vary significantly given the low speeds involved and will often depend on local topography.
Weather
Damp and murky to start on Friday, with cloud very gradually lifting through the morning. Although brightening up very slowly, cloud is likely to persist around the higher slopes in the north, whereas the best chance of any sunshine will be in the south but will come with a risk of isolated showers developing in the afternoon. Mist potentially forming in valleys during the evening given developing clear intervals.
Chance of cloud-free hill tops
Near nil becoming 40% by lunchtime in the north but 70-90% in the south.
Low cloud and visibility
Extensive low cloud down to valley floors in places during early morning, offering a significant impediment to visibility. Cloud rising to broken around 800 metres at best, with visibility perhaps good below this once drizzle passes.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
Likely another misty and murky start, with cloud at or near valley floors in places. Becoming drier and brighter through the morning, with cloud perhaps clearing higher ground in contrast to Friday, however there is also a much greater risk of showers developing, potentially eventually becoming heavy and slow-moving in places during the afternoon. Drier again during the evening, with a risk of valley mist and fog once again.
Chance of cloud-free hill tops
Near nil improving 80%.
Maximum wind speed expected
Northeasterly 15mph.
Temperature
- At 800m Plus 11 Celsius.
- Valley Plus 6 becoming 18 Celsius
- Freezing level Well above the summits.
Low cloud and visibility
Very poor visibility and extensive low cloud down to valley floors in places will lift to clear the highest ground mid-morning. More localised and temprary falls are possible in afternoon showers, with visibility otherwise good.
Mountain weather information
Sun 19 May
Sunrise:
Sunset:
Note that there is low confidence in detail for this period as a whole. Freezing level well above the summits throughout this three-day outlook. Mist and fog likely early iand late in an otherwise brighter day with higher cloud and perhaps some sunny spells. Small chance of light showers, with winds light to moderate northeasterly.
Mon 20 May
Sunrise:
Sunset:
Similar to Sunday - mist and fog early and late, with some brighter interludes as cloud breaks in places. Probably staying dry. Light to moderate easterly winds.
Tue 21 May
Sunrise:
Sunset:
More unsettled conditions probably making inroads from the west through Tuesday, with early mist and cloud giving way to limited brighter spells before a risk of rain and heavy, perhaps thundery showers later. Light southeasterly winds.
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.