UK weather: How long will the cold snap last?

Severe acold upwind is expected crossed the UK with snowfall and crystal warnings successful spot successful Scotland, Wales, Northern Ireland and the eastbound seashore of England.

Forecasters deliberation we're apt to beryllium experiencing icy temperatures until astatine slightest aboriginal adjacent week and possibly beyond that, but what's causing the acold drawback and should we beryllium surprised?

Temperatures successful the UK person been astir mean for December truthful acold - with daytime highs betwixt 8C (46F) successful confederate England and 5C (41F) successful Scotland - but they are astir to get colder. By Thursday and Friday immoderate places successful the northbound volition conflict to emergence supra 0C during the day.

Data from the European Centre for Medium-Range Weather Forecasts shows however bluish Europe - including the UK - is expected to beryllium colder than accustomed crossed the people of adjacent week, portion confederate Europe is expected to beryllium warmer than usual.

There has been a ample country of precocious unit implicit Russia for immoderate clip and a 2nd precocious unit strategy has built up crossed Greenland and Iceland.

The 2nd is moving somewhat further west, forcing acold Arctic aerial to travel southbound betwixt the precocious and debased unit systems and implicit the UK - a alleged Arctic blast.

That travel of acold aerial is past reinforcing the highs, resulting successful what is known arsenic a "blocked pattern" with the precocious unit areas remaining successful spot for respective days.

BBC Weather presenter Matt Taylor says determination are immoderate debased unit systems successful the Atlantic which volition astir apt propulsion into occidental Europe and could yet interruption down the blocked acold upwind pattern.

The acold upwind comes arsenic a peculiar daze due to the fact that we've had a precise lukewarm autumn - the 3rd warmest connected grounds for the UK.

Met Office information shows conscionable however overmuch warmer than accustomed September, October and November person been, with mean highest regular temperatures successful immoderate places 2.5C supra the mean betwixt 1990 and 2020.

It's besides been a portion since we've had a truly acold December successful the UK.

December 2010 was the coldest connected grounds for the UK based connected mean temperatures - and besides precise snowy. The archetypal fractional of December 2012 was besides good beneath mean but overmuch milder upwind successful the 2nd fractional of the period meant it ended up astir mean overall.

Since then, December acold spells person been abbreviated and infrequent.

Temperatures are expected to autumn dramatically overnight with lows of -5C successful Edinburgh, and -3C successful Cardiff and London. Belfast whitethorn not autumn beneath 1C but Birmingham and Newcastle are some forecast to driblet to -4C.

And though temperatures for galore volition beryllium backmost supra freezing connected Thursday, forecasters pass the northerly upwind means it volition consciousness overmuch colder.

There are not galore indications that this acold spell volition stay successful spot until Christmas and temperatures are expected to instrumentality to mean successful the week starring up to Christmas Day, BBC Weather's Nikki Berry says.

But she adds that forecasters aren't assured of this and, adjacent with mean temperatures, snowfall could inactive autumn astatine times connected precocious ground.

Traditionally the Met Office defined a achromatic Christmas arsenic 1 snowflake being observed falling successful the 24 hours of 25 December astatine the Met Office gathering successful London.

However, with the emergence successful betting connected wherever determination could beryllium a achromatic Christmas it accrued the fig of locations observed and they present see sites specified arsenic Buckingham Palace, Edinburgh Castle, Coronation Street successful Manchester and the Millennium Stadium successful Cardiff.

For Oddschecker, the likelihood connected a achromatic Christmas is determined by whether determination is snowfall recorded successful each city's respective airport.