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Snowdonia

Confidence

High for unsettled conditions through the coming days but lower regarding timing of rain and cloud details.

  • This evening
  • Thursday
  • Friday
  • Further outlook

Wednesday 15 August 2018

Sunrise: 05:56   Sunset: 20:44
Moon phase: Waxing crescent

Cloudy with outbreaks of occasionally heavy rain and extensive hill fog. Southwesterly gales slowly easing.

Thursday 16 August 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.

Strong sunlight Medium 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.

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.

Heavy persistent rain Low likelihood Show detail

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.

Headline

A bright day with sunny spells and occasionally heavy, blustery showers

Weather at 800m

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00
Heavy rain Heavy rain Cloudy Sunny intervals Sunny intervals Light shower day Sunny intervals Partly cloudy night
80% 60% 30% <05% 10% 30% 20% <05%
Chance of precipitation
2,800 2,200 1,700 1,700 1,800 1,900 2,000 1,900
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 SW 28 34 W 26 32 W 25 30 W 25 31 W 25 31 W 24 30 W 20 25 W 22 26
600m SW 20 25 W 19 24 W 16 21 W 18 24 W 19 26 W 18 25 W 15 19 W 14 17
300m SW 11 21 W 10 20 W 8 18 W 11 22 W 12 24 W 11 23 W 8 17 W 6 13
Valley SW 11 21 W 11 20 W 8 18 SW 11 23 W 12 24 W 11 24 W 9 18 W 7 14

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 11 9 7 6 8 9 8 8
600m 12 11 9 9 11 11 11 11
300m 14 13 12 12 14 15 14 13
Valley 15 14 13 14 15 16 15 14

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 6 5 2 1 3 4 4 4
600m 9 8 6 6 7 8 8 8
300m 13 11 10 10 11 13 12 12
Valley 14 13 11 12 13 14 14 13
Sunrise: 05:58   Sunset: 20:42
Moon phase: Waxing crescent

Weather

Cloud, occasionally heavy rain and hill fog clearing gradually clearing through the early hours with clear spells developing. Remaining cloud in the east soon clearing to leave a bright and dry morning with some good spells of sunshine. A few showers are likely through the afternoon but many places will remain dry. Any showers die out through the evening with some long clear spells.

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

Around 25% at first in the east with periods above about 600m, otherwise around 75% with occasional cloud above 750m.

Visibility

Several kilometres in rain and perhaps in showers, otherwise very good

Meteorologist's view

Gusts around 45mph over ridges and summits, especially through the morning and near showers, with lowering temperatures making it feel rather cold on the higher summits. Valley temperatures rising to around 19 Celsius by day.

Ground conditions

No recent ground conditions report available. For archived reports see - http://www.snowdonia.gov.wales/visiting/walking/ground-conditions

Friday 17 August 2018

Sunrise: 06:00   Sunset: 20:40
Moon phase: Waxing crescent

Weather

Cloud, especially across western hills, increasing through the early hours with patchy drizzle possible. Then a bright start in the east but thickening cloud brings outbreaks of rain and drizzle, most persistent across western hills. Some drier and brighter interludes are possible in the east during the afternoon.

Maximum wind speed expected

Westerly 15-20mph backing southwesterly 25mph, with gusts around 45mph, by early afternoon.

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

Around 25% in the west at first with periods of cloud above 600m falling to near zero with periods or persistent cloud above 450m and patches below. Eastern hills see chances nearer 60% at first with occasional or periods of cloud above 750m falling to 25% with cloud lowering to 600m at times.

Temperature

  • At 800m Plus 10 Celsius
  • Valley Around plus 10 Celsius at dawn rising to plus 18 or 19 Celsius by day
  • Freezing level Above the summits

Visibility

Good or very good, especially in the east at first, becoming several kilometres in rain and drizzle

Saturday 18 August 2018

Sunrise: 06:02   Sunset: 20:38
Moon phase: First quarter

Cloud and occasional rain gradually clearing through the morning then a drier and brighter afternoon, especially in the east. Strong southwesterly winds easing. Freezing level above the summits.

Sunday 19 August 2018

Sunrise: 06:03   Sunset: 20:36
Moon phase: First quarter

Occasionally heavy rain spreading east overnight, the rain then turning lighter and patchier for the afternoon with some brighter spells possible. Occasionally strong southerly winds turning more westerly and easing. Freezing level above the summits.

Monday 20 August 2018

Sunrise: 06:05   Sunset: 20:33
Moon phase: First quarter

Rather cloudy morning with patchy rain and drizzle but becoming brighter in the afternoon. Westerly or southwesterly winds continuing to ease. Freezing level above the summits.

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