Eryri / Snowdonia National Park
Includes all summits in the the northern half of Wales from Pumlumon northwards.
Wednesday's Forecast
Gale force, walking difficult
Challenging conditions, walking into the wind will be strenuous on exposed terrain, gusts may blow you over. 35 to 55mph.
Snow and rain mix
Precipitation falling mostly as snow over higher ground, but wetter lower down with sleet or mostly rain on lowest terrain. The freezing level may vary locally and during the course of the day.
Very Cold
Very low air temperatures or feeling bitterly cold due to wind chill on the mountains. Difficult conditions. Frostbite and hypothermia risk. Suitable protective clothing is required.
Winter kit required
Extensive frozen mountain terrain with snow cover. Safe progress will require spikes, crampons and ice-axe where necessary.
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Gale force, walking difficult
Challenging conditions, walking into the wind will be strenuous on exposed terrain, gusts may blow you over. 35 to 55mph.
Snow and rain mix
Precipitation falling mostly as snow over higher ground, but wetter lower down with sleet or mostly rain on lowest terrain. The freezing level may vary locally and during the course of the day.
Very Cold
Very low air temperatures or feeling bitterly cold due to wind chill on the mountains. Difficult conditions. Frostbite and hypothermia risk. Suitable protective clothing is required.
Winter kit required
Extensive frozen mountain terrain with snow cover. Safe progress will require spikes, crampons and ice-axe where necessary.
Viewing Forecast For
Eryri / Snowdonia National Park
Wednesday 6th December 2023
Last updated
Tue 5th Dec 23 at
4:28PM
Summary for all mountain areas
After a hard frost, mostly dry and bright, but feeling increasingly bitterly cold as southeasterly winds strengthen and cloud thicken through the day ahead of a front, which will bring and increasing risk of upland snowfall, in across western mountains toward evening, and then spreading to all parts overnight.
Headline for Eryri / Snowdonia National Park
Early sun, then overcast. Bitter chill as winds strengthen. Upland snow later.
How windy? (On the summits)
Southeasterly, strengthening through day from around 30mph after dawn to 40 to locally 50mph before dusk.
Effect of the wind on you?
Walking increasingly difficult, in places on lower slopes, and feeling bitterly cold as wind chill becomes significant.
How Wet?
Dry much of day, then periods of snow from late afternoon; whiteout
Dry for much of daylight, but fronts edging in from southwest will bring rain and persistent upland snow from mid to late afternoon, giving whiteout. Reverting to rain to all levels overnight.
Cloud on the hills?
Hills may be cloud free; before lowering to blanket the hills
Summits likely to start cloud free in the morning. Will deteriorate, during afternoon when snow arrives as cloud lowers to 300m or lower east Wales and 450 to 650m west.
Chance of cloud free summits?
70% lowering later in afternoon to 10%
Sunshine and air clarity?
Early sun, but soon overcast as cloud thickens. Appalling or near zero visibility in the upland snow that arrives late in the afternoon.
How Cold? (at 900m)
-1 or 0C (only a degree or so warmer in valleys). Will feel as cold as minus 16C directly in the wind.
Freezing Level
Almost all terrain at least partly frozen.
Viewing Forecast For
Eryri / Snowdonia National Park
Thursday 7th December 2023
Last updated
Tue 5th Dec 23 at
4:28PM
How windy? (On the summits)
Very turbulent conditions developing. Southeasterly, later southerly, winds; lifting through day to 50 to 70mph.
Effect of the wind on you?
Be prepared for increasingly very difficult conditions, as turbulent and very powerful winds accelerate over the mountains.
How Wet?
Frequent rain, heavy at times.
Frequent spells of rain and drizzle through the day. May become heavy or intense later in the day as an active front moves in, perhaps with local thunder.
Cloud on the hills?
Extensive
Extensive hill fog from mid slopes upwards, perhaps lower slopes near west coast and more especially mid Wales.
Chance of cloud free summits?
20%
Sunshine and air clarity?
Overcast. Poor or very poor visibilities.
How Cold? (at 900m)
3C, Feeling closer to -15C in exposure to the wind.
Freezing Level
Above the summits, but ground from mid slopes up, still partially frozen, with slow-continued thaw.
Viewing Forecast For
Eryri / Snowdonia National Park
Friday 8th December 2023
Last updated
Tue 5th Dec 23 at
4:28PM
How windy? (On the summits)
Southerly 40 to 60mph at first, but as low tracks in, winds will veer southwesterly and ease 25 to 40mph, maybe less.
Effect of the wind on you?
Be prepared for difficult conditions with significant wind chill and buffeting. Slowly moderate into the afternoon.
How Wet?
Frequent, at times heavy, rainfall.
Low pressure will drive frequent, and at times heavy, rainfall into the area through the day. Setting in at times in the west.
Cloud on the hills?
Extensive
Extensive hill fog will cover the hills throughout the day. Mostly mid to upper slopes initially, but patches descending to lowers slopes in rain as winds veer.
Chance of cloud free summits?
20%
Sunshine and air clarity?
Little if any sun. Visibility often poor due to rain.
How Cold? (at 900m)
Around 3C, but feeling more like -10C or below in direct exposure to the strongest winds.
Freezing Level
Above the summits, with upper level terrain continuing to thaw out.
Planning Outlook
Unsettled conditions will prevail over the next week to 10 days, with periods of upland gales or severe gales with precipitation frequent, mostly rain, although intermittently snow Scottish Highlands, more rarely elsewhere. Driest conditions (relative to the average) will likely be in the northwest Highlands, given the often backed flow, as the low pressure areas track in.