Britons will bask in unseasonably warm weather of 15C (59F) this weekend - while across the Atlantic 50 million Americans face a massive winter storm expected to dump up to 3ft (90cm) of snow across the east coast.
A state of emergency has been declared throughout a vast swathe of the eastern seaboard, with individual states in near-shutdown after thousands of flights were cancelled, schools and government offices closed and sports and entertainment events called off.
Warnings are in place from Arkansas in the south to New York in the far north east, and millions of people have been stocking up on food and emergency supplies.
But while Americans face the prospect of one of the worst winters in years, temperatures almost 10C above the average will leave people in the UK enjoying spring-like weather.
Thermometers are likely to peak at 15C (59F) on Sunday, a far cry from the usual 6.5C (43.7F) in January, as a dip in the Atlantic jet stream pushes warmer weather over the UK from the South West.
This comes days after temperatures of minus 12.4C (9.7F) were recorded in Kinbrace, Highlands, on January 19, the coldest day of the year so far, when it was also minus 8.4C (16.9F) in Upper Lambourn, Oxfordshire.
US officials are expecting blizzard conditions to combine with brutally high winds, inland flooding, white-out conditions and the possibility of thunder snow - when lightning strikes through snowstorms - paralysing the eastern third of the US and potentially causing up to a billion dollars (£700 million) of damage.
Washington DC, which is further south than Madrid and Rome - where on Friday it was 11C (51.8F) and 13C (55.4F) respectively - is braced for more than 2ft (60cm) of snow and authorities are shutting the subway system until Sunday.
Forecasters believe it could threaten the previous snowfall record in the US capital of 28in (71cm) during a two-day period in January 1922.
Up to 18in (45cm) is also expected in Philadelphia, along with 1ft (30cm) in New York. But Boston, further north, which was hit badly by snowstorms last year, is unlikely to see major snow, with a peak of 4in (10cm) predicted.
The extreme weather is down to a collision of very warm and humid air flowing north from the Gulf of Mexico and meeting very cold air across the central northern states and south-eastern Canada, the Met Office said, but it will not affect the UK.
Here, rain on Friday will clear through the East in the afternoon, leaving a few showers in the North West overnight. Most parts will be dry on Saturday, with some rain in the South and West later.
Billy Payne, a forecaster with MeteoGroup, said: "Temperatures will be above average, with highs generally of 9C (48F) to 12C (53.6F), with most places falling in the range above the January average.
"Typically that is around 6.5C (43.7F) in London and most places 6C (42.8F) to 7C (44.6F) at this time of year, and around 8C (46.4F) in the South West.
"Sunday will be milder still, with extensive cloud and bits and pieces of light rain and drizzle, mostly in the North and West and over hills. It could be up to 15C (59F) in places, most likely in the South and West, reaching 11C (51.8F) to 14C (57.2F) locally."
The mild outlook will continue into next week, though heavy and prolonged rain is likely in the middle of the week, particularly in the North and West, with winds of up to 60mph. Temperatures will fall away again with some overnight frosts possible.
Mr Payne added: "In the next week or two flooding could become a concern again, especially for areas that have been previously affected this winter."