A thoroughly average winter is about to give way to a prolonged period of cold which could leave the country blanketed in snow, forecasters have warned.

The snow that closed the M62 last night, covering much of the Pennines, is likely to sweep across Wales and western parts of England tomorrow night and could presage more of the same for up to a month.

Temperatures are expected to continue to fall next week, leaving Britain shivering in conditions that are about 5C lower than average for early February. Some parts, especially on higher ground, are unlikely to rise above freezing even in daylight.

A cold weather warning has been issued by the Met Office for tomorrow through to Tuesday, with widespread frosts anticipated. Forecasters were assessing the weather warning overnight and fear it may have to be extended further into next week. On Monday morning several centimetres of snow could lie on the ground in western parts, especially Wales.

Ben Grey, a Met Office forecaster, said conditions for the past two months had been average, but the sudden chill of the next few days was likely to remain for a fortnight or more. The average daytime temperature for early February is about 8C but next week and beyond it was more likely to be "down to 2, 3 and 4C", he said.

"February looks like it's going to be on the cold side. There's a good deal of uncertainty but it does look likely we are coming into a cold spell with a distinct possibility we will see more snow, even in the southern and eastern areas."

Easterly winds rushing down from Russia are being blamed for the current cold snap.

Weather 3-day forecast

*Today Starts cold and frosty with some snow in west, warmer and cloudier in east.

*Tomorrow Dry and cold in east, rain turning to snow in west overnight. Rain in Scotland.