Ministers, business leaders and fuel firms should prepare now for the cold snap, said Ewen McCallum, chief meteorologist at the Met Office.
"The important thing is to give an amber alert to Government and to business, to the energy industry, to health, to be cautious and perhaps plan forward," he told BBC Radio 4's Today programme.
"We are working with the Department of Health and what we are finding is admissions to hospital increase dramatically and mortality actually goes up dramatically in cold weather so the vulnerable and the elderly certainly are at risk.
"But ... we don't want to cause a scare. This is really just forward planning to make sure that Government departments and business utilities have got their act together."
Mr McCallum said the Met Office calculations were 66% likely to be proved correct.
They are based on the "North Atlantic oscillation", a measure of sea temperatures which normally correlate with weather patterns.
At present the readings suggest there will be much less westerly wind, which brings milder air from the Atlantic.
"We are looking at a pattern that will give us much more of a Continental-type flow, with weather coming in from the east," Mr McCallum said.
"We have to be careful not to be too dramatic, 62-63 was a particularly cold winter. We are probably looking at winters going back to 95-96 which was colder.
"We have had a pattern of very, very mild winters over the last few years so this will come as a shock."
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