Mountain weather

Mountain weather

Eryri / Snowdonia

Confidence

High for overall evolution, moderate for location and duration of heaviest bursts of rain for Wednesday.

Sunrise: Sunset:
Sunrise: Sunset:
Mountain hazards

Mountain weather hazards

Hazards apply at or above 300m, reflecting the more severe conditions which can occur at altitude.

Heavy Persistent Snow
Heavy snow can lead to rapid changes in underfoot conditions and paths may become treacherous or hidden. It also brings very poor visibility and often makes navigation much more challenging. When deep snow accumulates progress is often time consuming and strenuous, significantly affecting the distance one can travel on foot. Deep drifts can develop if snow is combined with strong winds. A heightened avalanche risk is possible and avalanche reports should be consulted where available.
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.
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

Cloud and rain clearing to drier and brighter weather.

Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
Weather
(at 800m)
Weather symbols Heavy Rain Light rain Light rain showers Sunny intervals Sunny intervals Sunny intervals
Chance of
precipitation
(at 800m)
Chance of precipitation
≥95%
90%
40%
10%
10%
10%

Wind direction and speed

Altitude above mean sea level
Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
900m W 22mph knots
W
22mph
N 22mph knots
N
22mph
N 23mph knots
N
23mph
N 19mph knots
N
19mph
N 16mph knots
N
16mph
NE 12mph knots
NE
12mph
600m
600m W 15mph knots
W
15mph
NW 15mph knots
NW
15mph
N 18mph knots
N
18mph
N 15mph knots
N
15mph
N 8mph knots
N
8mph
E 4mph knots
E
4mph
300m
300m W 9mph knots
W
9mph
NW 10mph knots
NW
10mph
NW 13mph knots
NW
13mph
N 11mph knots
N
11mph
NW 4mph knots
NW
4mph
SE 2mph knots
SE
2mph
Valley
Valley W 9mph knots
W
9mph
NW 10mph knots
NW
10mph
NW 14mph knots
NW
14mph
N 11mph knots
N
11mph
NW 5mph knots
NW
5mph
E 3mph knots
E
3mph

Wind gust

Altitude above mean sea level
Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
900m 26mph 26mph 29mph 24mph 20mph 16mph
600m
600m 18mph 19mph 23mph 20mph 11mph 6mph
300m
300m 16mph 17mph 22mph 18mph 10mph 4mph
Valley
Valley 16mph 17mph 22mph 18mph 10mph 4mph

Altitude above mean sea level
Time
Time
06:00
09:00
12:00
15:00
18:00
21:00
900m
900m 7 degrees Celsius 4 degrees Celsius 2 degrees Celsius 2 degrees Celsius 3 degrees Celsius 3 degrees Celsius
600m
600m 10 degrees Celsius 7 degrees Celsius 6 degrees Celsius 7 degrees Celsius 7 degrees Celsius 7 degrees Celsius
300m
300m 12 degrees Celsius 10 degrees Celsius 10 degrees Celsius 10 degrees Celsius 11 degrees Celsius 10 degrees Celsius
Valley
Valley 14 degrees Celsius 11 degrees Celsius 11 degrees Celsius 12 degrees Celsius 12 degrees Celsius 11 degrees Celsius
Freezing Level Freezing Level
2800m
2500m
1900m
1600m
1500m
1500m

Additional weather information

Meteorologist's view

Wet initially through the morning in the national park, making surfaces underfoot potentially slippery. Low cloud will also lead to poor visibilities on the highest routes. Through the afternoon conditions will turn much better within the park, however UV is still expected to be moderate to high so sun protection is advised.

Weather

Cloudy wet start to Wednesday with extensive low cloud shrouding summits. This accompanied by heavy bursts of rain. This will clear to the southeast through the morning allowing skies to turn brighter with lengthy sunny periods developing in the afternoon and evening

Chance of cloud-free hill tops

10% gradually rising to >95% by the afternoon.

Low cloud and visibility

Cloud bases initially 500m. Through the morning cloud is expected to clear and lift above summits. Moderate visibility initially becoming poor or very poor in cloud. Visibilities becoming very good or excellent through the afternoon with views of distant peaks increasingly likely.

Ground conditions

No recent ground conditions report available.

Summit specific forecast