Eryri / Snowdonia

This evening forecast

Brightness fading as cloud thickens with showery rain by midnight.

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.

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.

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.

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.

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

Heavy rain slowly easing but staying damp and blustery with drizzle at times.

Time	Time	00:00	03:00	06:00	09:00	12:00	15:00	18:00	21:00
Weather (at 800m)	Weather symbols
Chance of precipitation (at 800m)	Chance of precipitation	90%	≥95%	≥95%	80%	70%	60%	40%	30%

Wind direction and speed

Altitude above mean sea level

Time	Time	00:00	03:00	06:00	09:00	12:00	15:00	18:00	21:00
900m	900m	SW 25mph knots SW 25mph	SW 27mph knots SW 27mph	S 30mph knots S 30mph	SW 33mph knots SW 33mph	SW 28mph knots SW 28mph	SW 24mph knots SW 24mph	SW 26mph knots SW 26mph	SW 25mph knots SW 25mph
600m	600m	SW 16mph knots SW 16mph	SW 16mph knots SW 16mph	S 21mph knots S 21mph	SW 23mph knots SW 23mph	SW 20mph knots SW 20mph	SW 18mph knots SW 18mph	SW 16mph knots SW 16mph	SW 16mph knots SW 16mph
300m	300m	SW 10mph knots SW 10mph	SW 9mph knots SW 9mph	S 13mph knots S 13mph	SW 15mph knots SW 15mph	SW 14mph knots SW 14mph	SW 13mph knots SW 13mph	SW 11mph knots SW 11mph	SW 10mph knots SW 10mph
Valley	Valley	SW 10mph knots SW 10mph	SW 9mph knots SW 9mph	S 12mph knots S 12mph	SW 14mph knots SW 14mph	SW 13mph knots SW 13mph	SW 12mph knots SW 12mph	SW 10mph knots SW 10mph	S 10mph knots S 10mph

Wind gust

Altitude above mean sea level

Time	Time	00:00	03:00	06:00	09:00	12:00	15:00	18:00	21:00
900m	900m	30mph	33mph	37mph	41mph	36mph	32mph	33mph	32mph
600m	600m	21mph	21mph	27mph	30mph	27mph	26mph	23mph	23mph
300m	300m	19mph	19mph	24mph	27mph	25mph	23mph	21mph	20mph
Valley	Valley	19mph	18mph	23mph	25mph	24mph	21mph	20mph	20mph

Altitude above mean sea level

Time	Time	00:00	03:00	06:00	09:00	12:00	15:00	18:00	21:00
900m	900m	10 degrees Celsius	10 degrees Celsius	11 degrees Celsius	12 degrees Celsius	13 degrees Celsius	13 degrees Celsius	13 degrees Celsius	12 degrees Celsius
600m	600m	12 degrees Celsius	12 degrees Celsius	13 degrees Celsius	14 degrees Celsius	14 degrees Celsius	15 degrees Celsius	15 degrees Celsius	14 degrees Celsius
300m	300m	14 degrees Celsius	14 degrees Celsius	14 degrees Celsius	16 degrees Celsius	16 degrees Celsius	17 degrees Celsius	17 degrees Celsius	16 degrees Celsius
Valley	Valley	15 degrees Celsius	15 degrees Celsius	15 degrees Celsius	17 degrees Celsius	18 degrees Celsius	19 degrees Celsius	18 degrees Celsius	17 degrees Celsius
Freezing Level	Freezing Level	2700m	2800m	3200m	3100m	3100m	3100m	3200m	3100m

Altitude above mean sea level

Time	Time	00:00	03:00	06:00	09:00	12:00	15:00	18:00	21:00
900m	900m	6 degrees Celsius	6 degrees Celsius	6 degrees Celsius	7 degrees Celsius	8 degrees Celsius	9 degrees Celsius	9 degrees Celsius	8 degrees Celsius
600m	600m	9 degrees Celsius	9 degrees Celsius	9 degrees Celsius	10 degrees Celsius	11 degrees Celsius	12 degrees Celsius	12 degrees Celsius	12 degrees Celsius
300m	300m	12 degrees Celsius	12 degrees Celsius	12 degrees Celsius	14 degrees Celsius	14 degrees Celsius	15 degrees Celsius	16 degrees Celsius	15 degrees Celsius
Valley	Valley	14 degrees Celsius	14 degrees Celsius	14 degrees Celsius	15 degrees Celsius	16 degrees Celsius	17 degrees Celsius	17 degrees Celsius	16 degrees Celsius
Freezing Level	Freezing Level	2700m	2800m	3200m	3100m	3100m	3100m	3200m	3100m

Additional weather information

Meteorologist's view

A very wet start to the day with the potential for streams to rise rapidly and spate. Be prepared for surface water running over paths and slippery rock surfaces. Winds may gust close to 50 mph for a time over the highest summits during the morning, before easing and this will give considerable buffeting and make walking difficult in places. Waterproof and windproof clothing will be essential. Extensive hill fog will make route finding difficult and therefore the use of a compass and a map may be required for navigation.

Weather

Increasingly wet through the early hours with heavy rain developing, turning persistent by the end of the night. A very wet start to the morning but the rain easing by mid-morning and turning more showery. Occasional drier spells through the rest of the day, but frequent showers or spells of light drizzle, especially in the west. Glimmers of sunshine possible in eastern areas during the afternoon and evening.

Chance of cloud-free hill tops

10%, becoming 30% east.

Low cloud and visibility

Persistent and extensive cloud above 300-400m (400-600m in the east). This will give widespread fog and reduce visibility to poor or very poor. Occasional poor or very poor visibility at valley level too in periods of rain and drizzle but tending to become mostly good or very good visibility at lower levels later in the day.

Ground conditions

Please see - https://yrwyddfa.live/

Mountain weather information

Weather

A somewhat drier day is currently anticipated with a few morning showers possible. Perhaps turning more generally wet by the evening. Occasional brighter intervals, mainly in the east.

Chance of cloud-free hill tops

30% becoming 60% in the east.

Maximum wind speed expected

Southwesterly 25 mph gusting 40 mph, easing then strengthening again by the evening.

Temperature

At 800m Plus 11 Celsius.
Valley Plus 15 Celsius rising to plus 19 Celsius.
Freezing level Well above the summits.

Low cloud and visibility

Periods of cloud, persistent and extensive in the west, above 400-600m. Lifting to periods above 500-700m and locally clearing in the afternoon in the east. Often good or very good visibility at lower levels but widely poor or very poor in cloud with mist or fog and occasionally moderate in showers and evening rain,

Ground conditions

No recent ground conditions report available.

Mountain weather information

Fri 4 Sep

Sunrise: 06:31

Sunset: 19:58

Overnight rain gradually clearing through the morning. Staying cloudy for a time but gradually brightening up later. Moderate to fresh westerly winds and turning cooler.

Sat 5 Sep

Sunrise: 06:32

Sunset: 19:55

Largely dry with a mixture of cloud and sunny intervals. Some rain is possible later. Moderate westerly winds.

Sun 6 Sep

Sunrise: 06:34

Sunset: 19:53

A lot of uncertainty but probably cloudy with rain at times, most persistent in the west. Fresh to strong southerly winds.

Mountain weather

Eryri / Snowdonia

Confidence

This evening forecast

Mountain weather hazards

Poor Visibility

Heavy Persistent Rain

Gales

Severe Chill Effect

Strong Sunlight

Mountain weather forecast

Wind direction and speed

Wind gust

Additional weather information

Meteorologist's view

Weather

Chance of cloud-free hill tops

Low cloud and visibility

Ground conditions

Mountain weather information

Weather

Chance of cloud-free hill tops

Maximum wind speed expected

Temperature

Low cloud and visibility

Ground conditions

Mountain weather information

Fri 4 Sep

Sat 5 Sep

Sun 6 Sep

Summit specific forecast

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Mountain weather

Eryri / Snowdonia

Confidence

This evening forecast

Mountain weather hazards

High likelihood: 1 weather hazards

Poor Visibility

Medium likelihood: 1 weather hazards

Heavy Persistent Rain

Low likelihood: 3 weather hazards

Gales

Severe Chill Effect

Strong Sunlight

Mountain weather forecast

Wind

Wind direction and speed

Wind gust

Temperature

Feels Like Temperature

Additional weather information

Meteorologist's view

Weather

Chance of cloud-free hill tops

Low cloud and visibility

Ground conditions

Mountain weather information

Weather

Chance of cloud-free hill tops

Maximum wind speed expected

Temperature

Low cloud and visibility

Ground conditions

Mountain weather information

Fri 4 Sep

Sat 5 Sep

Sun 6 Sep

Summit specific forecast

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