The first real blast of winter will hit Britain today, leaving the country in the grip of severe frosts and treacherous icy conditions, forecasters warned.

Weeks of unusually mild temperatures will give way to a cold snap and freezing overnight temperatures.

Forecasters say the mercury will plummet to -5C (23F) tonight and -4C (25F) on Saturday night.

Although snow is not expected, weather experts say the sudden plunge in temperatures could cause severe ground frosts, icy road conditions and freezing fog patches.

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Temperatures in Shropshire are predicted to fall to -4C (25F) tonight and -1C (30F) overnight on Saturday.

Daytime temperatures are also in line for a dip, with highs of only 4C (39F), and along with brisk winds will make it feel much colder, forecasters said.

A spokesman from the Met Office said: “We expect some hard frosts and treacherous driving conditions.

“Dense freezing fog will descend, along with icy stretches on the roads and treacherous pavements.

“Add in a keen south easterly wind and the real feel by day across Britain won’t get much above freezing, with conditions nearing minus figures by night.”

West Midlands Ambulance Service urged people, especially drivers, not be caught out by the sudden drop in temperatures.

Tracey Morrell, assistant chief ambulance officer, said: “Every time we have a frost, West Midlands Ambulance Service ends up having to respond to a number of road traffic collisions where the wintry weather often plays a part.

“After weeks of above average temperatures, people need to remember to take extra care if there is frost on the ground.

“Drivers need to remember that it may take longer to slow down if it is icy.

“Equally, it is worth slowing down and also increasing the distance between your vehicle and the one in front.

“This may sound like common sense, and to be honest, it is.

“However, people have to remember that experience tells us that the number of road traffic collisions we get called to always rises when it is frosty.”