Snowdonia National Park

Includes all summits in the the northern half of Wales from Plynlimon northwards.

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Viewing Forecast For

Snowdonia National Park
Friday 14th August 2020
Last updated Thursday 13th August 2020 at 2:26 PM

Summary for all mountain areas

Many mountains dry; warm sunshine in the west. Low risk of isolated thundery showers forming. Greater threat of thunderstorms mid & south Wales. Fog persists in eastern Scotland and England from low levels upward; just some highest tops above this layer.

Headline for Snowdonia National Park

Risk of heavy rain and thunderstorms, locally varied. Gusty in places.

How windy? (On the summits)

East or northeasterly 15mph, but locally 25mph - strongest winds may extend to some lower slopes.

Effect of the wind on you?

Mostly small - although sudden buffeting in gusts some lower slopes.

How Wet?

Local thundery downpours; may become focused toward mid-Wales

Remnants of thunderstorms will drift about slowly from dawn, bringing a mix of pockets of light rain, but also patches of heavy rain. From about midday, risk of renewed thunderstorms bringing local heavy rain, the risk greatest across mid-Wales. Some areas may well escape dry for many hours.

Cloud on the hills?

Summits clearing intermittently

Ribbons of fog from some valleys up after dawn, extensive some higher areas. Nevertheless, some summits cloud free (in places above the fog). Will vary during the day as rain comes and goes, at times cloud filling in from lower slopes up, but particularly W Wales, sometimes clearing.

Chance of cloud free summits?

40%

Sunshine and air clarity?

Occasional sunshine. Hazy or very hazy; visibility very poor in heavy rain.

How Cold? (at 900m)

17C, small diurnal range; locally a degree or so lower if in fog banks.

Freezing Level

Above the summits.

Viewing Forecast For

Snowdonia National Park
Saturday 15th August 2020
Last updated Thursday 13th August 2020 at 2:26 PM

How windy? (On the summits)

Easterly; speeds varied, typically 20mph but locally up to 30mph on higher slopes and in sudden gusts some lower slopes.

Effect of the wind on you?

Generally small, albeit both higher up and on lower slopes (particularly through passes and cols and west of higher tops).

How Wet?

Areas of rain, some thundery

A mix of areas of constant rain over a few hours and heavy briefer bursts with threat thunderstorms. Least rainfall likely north from Snowdon.

Cloud on the hills?

Summits intermittently clearing

Confidence in detail low: broadly areas of fog from lower slopes up at first and in some areas in and after rain. However, particularly in west Wales, higher summits may clear for periods.

Chance of cloud free summits?

30%

Sunshine and air clarity?

Little or no sunshine. Hazy and visibility locally poor in heavy rain.

How Cold? (at 900m)

12C; small variation all day.

Freezing Level

Above the summits

Viewing Forecast For

Snowdonia National Park
Sunday 16th August 2020
Last updated Thursday 13th August 2020 at 2:26 PM

How windy? (On the summits)

East to southeasterly, 15 to 25mph, but locally may be gusty to 30-35mph near/west of higher ridges and summits.

Effect of the wind on you?

Mostly small, but local buffeting gusts possible, in places to low levels.

How Wet?

Risk bursts of rain

Detail uncertain: Some areas may escape often dry, but a risk of bursts of rain extending northwards across Wales through the day, risk thundery.

Cloud on the hills?

May persist some hills

Banks of low cloud most extensive and persistent across eastern hills in Wales, particularly around rain, forming to low levels. Further west, patchy cloud, with breaks to higher slopes at times.

Chance of cloud free summits?

60%

Sunshine and air clarity?

Probably little sun due to layers of high cloud. A general haze, and visibility reduced further where rain occurs.

How Cold? (at 900m)

Staying around 12C.

Freezing Level

Above the summits.

Planning Outlook

Remaining warm and humid through the weekend, particularly in western regions, whilst eastern areas are cooler under North Sea air, which brings a risk of lingering fog banks. The Scottish Highlands stay extensively dry. Thundery rain mostly confined to Wales, although rain may expand back northwards into the Pennines by Sunday. Into next week, light winds and areas of slow-moving showers at first, then a gradual change is likely as windier conditions move in from the Atlantic, with belts of rain or showers.