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Snowdonia - Mountain weather forecast

Weather warnings

Warnings affecting Snowdonia over the next 5 days

Confidence

High for unsettled theme throughout, and for a very mixed day on Friday. Also high for a dry start Saturday, but confidence is low regarding timing and extent of rainfall later in the day. Confidence then remains very low with the details and timings thereafter.

  • Friday
  • Saturday
  • Further outlook

Friday 18 August 2017

Weather hazards

Gales Medium likelihood Hide detail

Progress will be impeded by very strong winds. Walking will be difficult and strenuous at times with a potential for one to be blown over in gusts. There can be a marked increase in winds through cols or on exposed ridges and summits. Distances often take longer to cover with compass bearings becoming more difficult to follow accurately.

Learn more about gales

Poor visibility Low likelihood Show 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.

Learn more about poor visibility

Thunderstorms Low likelihood Show detail

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.

Learn more about thunderstorms

Heavy persistent rain Low likelihood Show detail

Prolonged exposure to heavy rain can result in drenched clothing and a risk of hypothermia if not wearing good quality waterproofs. Terrain may turn increasingly boggy underfoot, while mountain streams will rapidly rise into spate and may 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.

Learn more about heavy persistent rain

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.

Learn more about strong sunlight

Forecast

Windy with sunny spells and showers Risk of more organised showers this afternoon.

Weather

06:00 09:00 12:00 15:00 18:00 21:00
Weather at 800m Light shower day Light shower day Heavy shower day Heavy rain Heavy rain Light shower night
Chance of precipitation at 800m 40% 40% 60% 70% 70% 50%

Wind speed and direction

06:00 09:00 12:00 15:00 18:00 21:00
Altitude above mean sea level
900m W 31 37 W 31 38 SW 32 41 SW 36 45 W 33 42 W 33 42
600m SW 22 27 W 23 30 SW 25 33 SW 26 35 W 25 33 W 21 29
300m W 13 25 W 14 27 SW 15 30 SW 15 33 W 13 31 W 8 26
Valley W 19 34 W 23 40 SW 22 38 SW 26 46 SW 20 36 W 20 37

Temperature

06:00 09:00 12:00 15:00 18:00 21:00
Altitude above mean sea level
900m 6 ° 6 ° 7 ° 7 ° 8 ° 7 °
600m 8 ° 8 ° 9 ° 9 ° 10 ° 9 °
300m 11 ° 11 ° 12 ° 12 ° 12 ° 11 °
Valley 11 ° 13 ° 14 ° 13 ° 12 ° 12 °

Feels like temperature

06:00 09:00 12:00 15:00 18:00 21:00
Altitude above mean sea level
900m 1 ° 0 ° 1 ° 1 ° 2 ° 2 °
600m 4 ° 4 ° 5 ° 5 ° 6 ° 6 °
300m 9 ° 8 ° 10 ° 9 ° 9 ° 10 °
Valley 9 ° 11 ° 11 ° 10 ° 10 ° 10 °

Freezing level

06:00 09:00 12:00 15:00 18:00 21:00
Freezing level i 1,700 m 1,600 m 1,700 m 1,700 m 2,100 m 1,900 m
Sunrise: 06:02
Sunset: 20:38
Moon phase: Waning crescent

Weather

A bright, breezy start to the day is expected, although scattered showers and sunny spells will soon spread east, perhaps heavy at times. The odd rumble of thunder is also possible. Cloud will then thicken and descend onto the hills during the afternoon, with winds also likely to strengthen. A more organised spell of showery, heavy rain is possible, before gradually clearing east during the evening with clearer spells developing.

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

80% during the morning, with cloud obscuring some hills above 800m during showers. Decreasing to 40% during the afternoon, with cloud descending to around 500m. This then gradually clearing around and after dusk, with 60% chance of cloud free mountain tops by midnight.

Visibility

Good visibility at first, with distant hills visible, and only becoming hazy during showers. This reducing to moderate to poor, during the afternoon with only nearby peaks visible. Some very poor visibility possible across highest summits. Visibility then increasing again into the evening, as clouds clear.

Meteorologist's view

A very mixed day, with showers and rain interspersed with some drier, brighter intervals, leading to the potential for conditions to change rapidly. With winds perhaps 10-15mph stronger than indicated in the table above, especially across exposed ridges and summits, some care will be needed across any exposed sections at height.

Ground conditions

No adverse ground conditions reported on 18 of Aug

Saturday 19 August 2017

Sunrise: 06:03
Sunset: 20:36
Moon phase: Waning crescent

Weather

Dry overnight and breezy, however some summits are likely to remain shrouded in cloud. Sunny spells will develop through the morning. However cloud will thicken again and descend onto the slopes during the afternoon as a band of rain approaches from the east, perhaps reaching Snowdonia during the evening.

Temperature

  • At 800m Plus 8 Celsius becoming Plus 10 Celsius.
  • Valley Plus 7 Celsius becoming Plus 17 Celsius.
  • Freezing level Above the summits.

Visibility

Good to very good during the morning, with distant hills visible. Some minimal reduction likely during showers, but very poor when in amongst the cloud. Visibility reducing during any evening rain, with only moderately distant hills discernible.

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

80%, with some hills above 800m obscured. Increasing to 100% by midday. However cloud returning and descending on slopes during the afternoon, and falling to 40% by the evening with some hills as low as 500m obscured.

Maximum wind speed expected

West or north-westerly with gusts 35 to 40 mph possible across the highest tops early in the day.

Sunday 20 August 2017

Sunrise: 06:05
Sunset: 20:33
Moon phase: Waning crescent

A cloudy and humid start, with hills above 500m obscured, and outbreaks of drizzle likely. Winds strengthening ahead of a band of rain, turning heavy and persistent later in the day.

Monday 21 August 2017

Sunrise: 06:07
Sunset: 20:31
Moon phase: New

Further rain likely during the morning, and only clearing to showers later in the afternoon. However many hills likely remaining shrouded in cloud. Rain may well return late in the day.

Tuesday 22 August 2017

Sunrise: 06:08
Sunset: 20:29
Moon phase: New

Early cloud and rain will clear to sunny spells, and scattered showers. It is also likely to be feeling much fresher.

Issued at:

The Snowdonia mountains are made up of 90 mountain peaks including the tallest mountain in Wales, Snowdon, standing at 1,085 metres.

The region can be divided into four areas with the northernmost area the most popular, including peaks such as Moel Hebog, Mynydd Mawr and the Nantlle Ridge. Many hikers tend to concentrate on Snowdon itself regarding it as a fine mountain. However it can become quite crowded, with the peak welcoming around half a million visitors every year, of which four fifths scale the peak on foot, while the remainder choose to take the train instead.

One of Snowdon’s main attractions is the sheer number and variety of paths that reach the peak. This means that everyone from mountaineering novices to climbing experts should find a way up the mountain that will suit their abilities or provide them with a sufficient test. The easiest is the Llanberis path which, being the longest, has the most shallow ascent. In contrast, the Watkin Path is widely seen as being the most demanding ascent, despite also being considered the prettiest.

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