BRITAIN is on alert for a “major” Arctic freeze to bring sub-zero temperatures and snow after the weekend.
Icy gales threaten blizzard conditions in parts of the country with widespread hail and sleet forecast.
Snowfall will hit Scotland and high ground across northern England early next week before hail and sleet nudge further south, experts say.
The snow risk will escalate into next weekend with heavy flurries possible across Wales and central England.
A plume of cold air from the North Pole will start to push southwards through Britain from Monday experts warn.
Thermometers will nosedive to -6C (21.2F) overnight next week making Britain colder than Russia, Iceland and Greenland.
The almost summer-like conditions at the start of the month are about to become a distant memory as icy air floods in from the Arctic.
Daytime temperatures will struggle to get much above single figures after hitting a balmy 25.5C (77.9F) a fortnight ago.
Exacta Weather’s James Madden warned to brace for a “major winter blast” with snow and widespread frosts likely.
He said: “Although it may feel pleasant at times this week, a major blast of winter awaits and this could even bring some wintry or hefty hail showers to much lower levels of the country at times throughout next week.
“Southern parts are likely to fare better during this period, but the northern half of the country is likely to see frequent weather systems bringing in rain and some wintry weather or snow showers across higher ground in the north within this period.
“Some widespread frosts are also likely within this period under clearer skies and chilly northerly winds, in particular, in some rural areas but not restricted to these parts.
“Despite high pressure dominating with plenty of sunshine throughout the weekend – it is likely we will see some cooler and more showery weather and this is likely to persist into next week.”
The Weather Channel’s Brett Gibbons said freezing conditions will be compounded by heavy snow and thunder in parts.
He said: “Parts of the UK are set be battered by blizzards as a cold front drifts south across the country on a bitter Arctic wind.
“Temperatures will plunge early next week when the bitter weather system moves causing heavy snow to fall on Monday.
“Northwestern Britain and Ireland will get the worst of the wintry conditions, which also include the possibility of hail and thunderstorms.
“Snow may even fall at lower levels during the strong north-westerly breeze making it feel much colder.”
Fellow Weather Channel forecaster Eleanor Bel added: “High pressure over the south will shift southeastwards and allow a rapidly deepening area of low pressure to move from Iceland to the North Sea area.
“This will bring high winds with a significant wind chill to northern areas, as a cold front moves southwards across all areas to introduce colder air.
“Snow will be confined to the higher ground of Scotland initially but the snow level will gradually fall through Monday night into Tuesday where snow will reach lower levels in the heavier falls.”
Met Office figures reveal temperatures so far this month have been higher than usual for the time of year.
Britain has been around 1.1C warmer than normal for April while thermometers in East Anglia have stayed around 1.5C above average.
The Met Office said a cold front will move across Britain this weekend bringing chilly air in from the north.
Forecaster Oli Claydon said: “Towards the end of this week there is going to be a downturn in the weather.
“As we get into the weekend overnight temperatures are starting to drop before a cold front moves in on Monday bringing Arctic maritime air across the country.”
The Met Office said cold weather could hang around into the start of next month with a chilly outlook for the Mayday Bank holiday.
A spokesman added: “We are expecting Monday to be rather cold with a band of rain moving southwards, probably bringing the first rain of any note to southern areas for several weeks.
“It is likely to be very windy in Scotland and Northern Ireland with gales and showers, these wintry in the north.
“The rest of next week could well become even colder with a widespread risk of night frost. “Showers in the north are likely to be wintry mid-week and some hail and sleet may spread further south at times.
“Early May is likely to stay on the chilly side, with an ongoing risk of frost by night in a few places.”
Weather models show thermometers will plunge to -6C (21.2F) in central England next week with lows of -5C (23F) in the north and -2C (28.4F) in the south.
Snow is possible across Scotland and the north, central and western Britain and the south by the end of the week.
Ladbrokes has cut the odds on temperatures hitting -5C (23F) next week from 2/1 to 10/1 as forecasters deliver chilly predictions.
SpokeswomanJessica Bridge said: "April's taking a drastic turn for the worst, and the odds have followed suit.
Forecasters predict dry and mild conditions for this Sunday’s London Marathon with maximum temperatures of 14C (57.2F) forecast for London.