Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
High for a bright but showery theme in coming days. Moderate for shower details and extent of low cloud each night and early morning.
Mountain weather hazards
Hazards apply at or above 300m, reflecting the more severe conditions which can occur at altitude.
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.
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
Early cloud clearing to sunny spells and scattered heavy and thundery showers later.
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
Chance of precipitation (at 800m) |
20% | 10% | 40% | 40% | 30% | 20% |
Wind direction and speed (mph)
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
N
5
|
N
8
|
N
10
|
N
12
|
N
14
|
NE
15
|
| 600m |
N
4
|
N
9
|
N
11
|
N
12
|
N
12
|
N
9
|
| 300m |
NW
3
|
N
7
|
N
9
|
N
10
|
N
8
|
N
5
|
| Valley |
NW
3
|
N
7
|
N
9
|
N
9
|
NW
7
|
NW
4
|
Wind gust (mph)
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m | 6 | 10 | 16 | 18 | 19 | 20 |
| 600m | 5 | 12 | 16 | 18 | 17 | 13 |
| 300m | 4 | 10 | 14 | 15 | 14 | 10 |
| Valley | 4 | 10 | 15 | 15 | 11 | 7 |
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
10°
|
10°
|
12°
|
12°
|
12°
|
11°
|
| 600m |
11°
|
12°
|
14°
|
14°
|
14°
|
12°
|
| 300m |
11°
|
14°
|
17°
|
16°
|
16°
|
14°
|
| Valley |
11°
|
15°
|
17°
|
17°
|
16°
|
14°
|
| Freezing Level |
2,300m
|
2,300m
|
2,400m
|
2,500m
|
2,600m
|
2,400m
|
Altitude above mean sea level
| 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 | |
|---|---|---|---|---|---|---|
| 900m |
9°
|
8°
|
10°
|
10°
|
9°
|
8°
|
| 600m |
10°
|
10°
|
12°
|
12°
|
12°
|
10°
|
| 300m |
11°
|
13°
|
15°
|
15°
|
15°
|
13°
|
| Valley |
11°
|
14°
|
15°
|
15°
|
15°
|
14°
|
Additional weather information
Meteorologist's view
Hill fog may make navigation tricky if near summits around sunrise. Sun protection advised through the middle and latter part of the day. Torrential thundery downpours may create surface runoff and fast flowing watercourses locally later.
Weather
Low cloud covering summits during the first part of the morning. Cloud lifting and breaking a little after sunrise, with sunny intervals and a chance of showers developing in the afternoon across the park, some of which may be heavy and thundery. Bright through the afternoon, becoming increasingly dry, with sunny intervals. Moderate UV levels expected in the sunny intervals.
Chance of cloud-free hill tops
40% becoming 90% through the morning.
Low cloud and visibility
Cloud down to 700-800m through the early hours, soon rising to above summits in the hours after sunrise. Cloud should remain above summits even in in the heavier showers later. Visibility generally poor in early cloud at elevation otherwise good or very good with clear views of distant hills. Visibility dropping to moderate or poor in any of the heavy thundery downpours later.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
A dry day with long sunny spells. Warm with high UV levels.
Chance of cloud-free hill tops
95%
Maximum wind speed expected
Northeasterly 20mph.
Temperature
- At 800m Plus 4 Celsius becoming 16 Celsius.
- Valley Plus 11 Celsius becoming 20 Celsius.
- Freezing level Above summits.
Low cloud and visibility
Nil low cloud expected. Visibility good or very good with clear views of distant hills.
Mountain weather information
Mon 20 May
Sunrise:
Sunset:
Mist and fog possible early and late, with plenty of bright and sunny spells through the middle of the day. Probably staying dry. Light easterly winds. Freeing level above summits.
Tue 21 May
Sunrise:
Sunset:
A dry and bright start. The risk of showers increasing through the day, these may be heavy and thundery. Light and variable winds. Freezing level above summits.
Wed 22 May
Sunrise:
Sunset:
A dry start but increasingly cloudy day, with a risk of showers. Winds strengthening from the north. Freezing level above 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.