Overnight frosts are also set to become common, with temperatures plummeting well below freezing point.
Steve Willington, the organisation's chief forecaster, said: "The cold weather is clearly on its way this week, but it will take much of this week to reach all of the UK."
That could give homeowners just about enough time to make a switch of energy provider and pay less when they inevitably have to turn up the heating in a few days to deal with the cold.
As well as the weather, a reason to find the best deal is the rising price of energy, with Scottish Power's decision to increase its tariffs described recently by Consumer Focus's head of energy Audrey Gallacher as leaving people in "dismay".
Posted by Richard Eden
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