Mountain weather
Eryri / Snowdonia Mountain weather forecast table
Confidence
High for a day of sunshine and showers, but lower confidence on where the heaviest showers will form.
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.
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.
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
Sunny spells and showers, some heavy with hail and thunder.
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
Weather (at 800m) |
|
|
|
|
|
|
Chance of precipitation (at 800m) |
60% | 60% | 60% | 50% | 50% | 50% |
Wind direction and speed (mph)
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
N
11
|
N
8
|
N
8
|
N
9
|
NE
13
|
NE
14
|
| 600m |
N
7
|
N
7
|
N
8
|
N
9
|
N
9
|
E
6
|
| 300m |
N
4
|
N
5
|
N
7
|
N
9
|
N
8
|
NW
4
|
| Valley |
NW
4
|
N
6
|
N
8
|
N
9
|
N
8
|
NW
4
|
Wind gust (mph)
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m | 13 | 11 | 11 | 13 | 18 | 19 |
| 600m | 8 | 10 | 11 | 12 | 13 | 11 |
| 300m | 6 | 8 | 10 | 12 | 14 | 8 |
| Valley | 6 | 8 | 11 | 13 | 13 | 8 |
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
5°
|
6°
|
6°
|
7°
|
6°
|
6°
|
| 600m |
7°
|
8°
|
9°
|
9°
|
8°
|
8°
|
| 300m |
8°
|
10°
|
11°
|
12°
|
11°
|
10°
|
| Valley |
9°
|
11°
|
12°
|
13°
|
12°
|
11°
|
| Freezing Level |
1,800m
|
1,800m
|
1,800m
|
1,900m
|
1,800m
|
1,800m
|
Altitude above mean sea level
| Time | 06:00 | 09:00 | 12:00 | 15:00 | 18:00 | 21:00 |
|---|---|---|---|---|---|---|
| 900m |
1°
|
3°
|
4°
|
4°
|
2°
|
2°
|
| 600m |
5°
|
6°
|
7°
|
7°
|
6°
|
6°
|
| 300m |
7°
|
9°
|
10°
|
10°
|
9°
|
9°
|
| Valley |
8°
|
10°
|
11°
|
11°
|
11°
|
10°
|
Additional weather information
Meteorologist's view
The heavy showers are likely to contain hail and may also produce gusty winds, as well as dropping visibility quite quickly as they pass. A wet ground will make steeper slopes slippery underfoot.
Weather
Cloudy during the early hours, with outbreaks of rain and hill fog. Brightening up slowly through the morning, with sunny spells by lunchtime, but then an increasing risk of showers across the park. Some of the showers will be heavy during the afternoon and evening, with the risk of hail and thunder.
Chance of cloud-free hill tops
10% during the early hours, rising to 70% by late morning and into the afternoon.
Low cloud and visibility
Poor to very visibility during the early hours in hill fog. Generally good or very good during the day, but often dropping to moderate or poor in passing showers. Cloud bases 100m to 300m during the early hours, rising to 600m during the morning and then above the summits by early afternoon. However, cloud bases dropping back down to around 400m to 500m in passing showers.
Ground conditions
Please see - https://yrwyddfa.live/
Mountain weather information
Weather
Any overnight low cloud and drizzle should lift and break during the morning, to leave a drier and brighter afternoon for much of the park. The small risk of a few passing light showers.
Chance of cloud-free hill tops
40% during the early hours, rising to 80% during the morning and 90% for the afternoon.
Maximum wind speed expected
Northeasterly 10-15mph gusting 20-25mph.
Temperature
- At 800m Plus 3 Celsius, rising to plus 7 Celsius.
- Valley Plus 3 Celsius, rising to plus 16 Celsius.
- Freezing level Above the summits.
Low cloud and visibility
Cloud bases of 400m during the early hours, occasionally down to 300m. Lifting to 600m through the morning, but then should be above the summits in the afternoon. Poor to very poor visibility in the hill fog, but conditions improving into the afternoon with good visibility likely.
Mountain weather information
Tue 5 May
Sunrise:
Sunset:
Bright or sunny spells and scattered showers. Any passing showers may fall as snow over the summit of Yr Wyddfa. Fresh northerly winds across summits.
Wed 6 May
Sunrise:
Sunset:
Bright or sunny spells and scattered showers, with a fairly brisk northerly wind. Freezing levels will be near the summit of Yr Wyddfa so again any passing showers may fall as snow here.
Thu 7 May
Sunrise:
Sunset:
Bright or sunny spells and scattered showers. Winds light to moderate and more variable in direction. Freezing levels likely to lift 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.