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High for becoming cloudy with rain at times on Wednesday but becoming lower from Thursday regarding details and timing of precipitation due to uncertainties regarding development and movement of a low over the western UK.

  • This evening
  • Wednesday
  • Thursday
  • Further outlook

Tuesday 20 March 2018

Sunrise: 06:20   Sunset: 18:29
Moon phase: Waxing crescent

Dry and clear. Fresh northwesterly winds.

Wednesday 21 March 2018

Weather hazards

Poor visibility High likelihood Hide detail

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.

Severe chill effect Medium likelihood Show detail

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.

Gales Low likelihood Show detail

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.

Strong sunlight Low likelihood Show detail

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.


Dry start but increasing cloud brings outbreaks of rain and snow. Strengthening westerly winds.

Weather at 800m

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
Clear night Clear night Partly cloudy night Sunny intervals Cloudy Light snow Light rain Cloudy
00% 00% 00% <05% 30% 60% 70% 40%
Chance of precipitation
200 400 400 500 500 800 1,600 1,700
Freezing level (m)
The level above which snow is expected to settle or the ground is expected to be frozen

Wind speed and direction (mph) By altitude above mean sea level

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m W 13 15 W 17 20 W 16 20 W 20 26 W 20 27 W 23 30 SW 25 31 SW 23 29
600m SW 8 11 SW 11 14 SW 10 13 W 14 18 W 16 22 SW 17 23 SW 16 22 SW 14 21
300m S 3 6 SW 6 11 SW 5 9 W 8 15 W 10 19 SW 10 19 SW 10 19 SW 8 18
Valley S 4 7 SW 7 12 SW 5 10 W 8 15 W 11 20 SW 11 20 SW 11 21 SW 10 21

Temperature (°C) By altitude above mean sea level

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m -3 -3 -3 -2 -2 -1 0 1
600m -1 0 -1 0 1 1 2 3
300m 1 1 1 3 4 4 4 5
Valley 1 2 2 4 5 5 5 6

Feels like temperature (°C) By altitude above mean sea level

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
900m -8 -9 -10 -10 -9 -8 -7 -6
600m -5 -5 -6 -6 -5 -4 -3 -2
300m -1 -2 -2 -1 0 0 0 2
Valley 0 -1 -1 1 2 2 2 3
Sunrise: 06:17   Sunset: 18:31
Moon phase: Waxing crescent


Remaining dry but cloud increasing through the early hours, although clear spells may lead to some low level fog patches developing across the east of the area towards dawn. Then a bright morning, especially across the south and east but cloud continues to increase bringing outbreaks of snow from mid afternoon. During the late afternoon the snow turns increasingly to rain at all levels, the precipitation most persistent across northwestern hills. The evening remains cloudy with rain generally necoming patchier.

Chance of cloud-free mountain/hill tops at 800m

Around 80% through the morning with occasional cloud above about 750m but falling to near zero in the northwest and around 25% over southern and eastern hills as cloud becomes periods or persistent above 600m and lowers to 450m at times across northern and western hills.


Good or very good through the morning, although several hundred metres in early low level fog patches and cloud, becoming several kilometres in rain and snow.

Meteorologist's view

Overnight temperatures in eastern valleys likely to fall below freezing. Thaw of lying snow expected through the evening.

Ground conditions

Area - Snowdon Date - 20 March 2018 Time - 11.00am Snow Above - 850m Report By - Snowdon Warden Route Taken Llanberis Path Conditions Wet surfaces are coated in ice. Heavy frost cover on rocks and vegitation. Depth of snow increases with altitude. Snow drifts in areas. Slopes and paths paths covered in hard snow and ice. Kit Advice The following is a list of additional kit required based on the current conditions. Ice axe and crampons recommended. Wear crampon compatible boots. Wear sturdy walking boots. Take waterproofs, hat, gloves and spare warm layers.

Thursday 22 March 2018

Sunrise: 06:15   Sunset: 18:33
Moon phase: Waxing crescent


Outbreaks of rain largely dying out overnight but remaining cloudy with, especially for western and southern fells, patchy drizzle through the rest of the morning. More persistent and occasionally heavy rain, with some sleet or wet snow for a time on summits, arrives during the afternoon and evening.

Maximum wind speed expected

Westerly 20mph backing more southwesterly through the morning and increasing 35mph, with gusts around 50mph over ridges and summits through the afternoon and evenin.

Chance of cloud-free mountain/hill tops at 800m

Best chances, around 60% for a time, across eastern hills and, especially through the afternoon, northeastern hills with cloud becoming occasional above 750m, but little chance over western hills with periods or persistent cloud above about 450m for the most part.


  • At 800m Around plus 2 Celsius
  • Valley Falling to around plus 4 Celsius by dawn then rising to plus 12 Celsius in the east by day
  • Freezing level Falling to just above the highest summits for a time.


Very poor in cloud otherwise, especially across eastern hills, good or very good falling to several kilometres in rain and perhaps a kilometre in summit snow.

Friday 23 March 2018

Sunrise: 06:13   Sunset: 18:34
Moon phase: First quarter

Cloud and rain clearing northeast through the morning to leave a brighter afternoon with showers, these falling increasingly as sleet and snow above about 600m. Strong to gale force southerly or southwesterly winds easing. Freezing level falling to 750m.

Saturday 24 March 2018

Sunrise: 06:10   Sunset: 18:36
Moon phase: First quarter

Clear or sunny spells and showers, these falling increasingly as snow above 600m. Strong southwesterly winds easing. Freezing level around 750m.

Sunday 25 March 2018

Sunrise: 07:08   Sunset: 19:38
Moon phase: First quarter

Another day of sunny spells and showers, with snow above about 600m. Occasionally fresh westerly or southwesterly winds. Freezing level around 750m.

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