Summary for all mountain areas

A sudden change from the NW to all mountains: Temperatures will drop below freezing point; severe upland gales will be widespread, and concentrated on western mountains as far south as those near the N Irish Sea, frequent heavy snow/whiteout, hail and sometimes thunder.

Headline for Peak District and Yorkshire Dales

Frequent storm force upland winds; snow, hail; risk thunder.

How windy? (On the summits)

Westerly, in the range 45 to 65mph. Sudden squalls may bring gusts locally to 85mph.

Effect of wind on you?

Difficult walking conditions and severe wind chill even low levels. Any mobility often tortuous higher tops. Severe wind chill.

How Wet?

Frequent snow & hail; risk lightning

Bursts of rain at dawn. But soon sudden squalls of heavy snow and hail, sometimes merging into near constant snow over an hour or so. Intermittent whiteout; risk thunder, particularly Yorkshire Dales NP. particularly Peak District, there may be a few hours until into afternoon with little precipitation.

Cloud on the hills?

Often covering higher hills

Rapidly changing cloud base; extensively covering higher areas, and dropping below 450m near precipitation (especially afternoon). Breaks to higher tops.

Chance of cloud free summits?

30%

Sunshine and air clarity?

Occasional sunshine, mainly eastern dales and Peak District NP in morning. Visibility briefly excellent, but frequently appalling or near zero where in cloud and snow/blowing snow.

Temperature (at 600m)

Suddenly dropping from 6C at dawn to -2 or perhaps in afternoon -4C. Will feel as cold as minus 22C directly in the wind.

And in the valleys

Up to 9 or 10C at dawn. But soon dropping to in the range 1 to 4C - up and down as showers come and go.