The British the Met Office warned that an Arctic blast is hitting the UK, which could cause overnight temperatures as low as -10C by the end of the week.
Motorists could face treacherous conditions on the roads, with train journeys taking longer than usual.
The UK Health and Security Agency has issued a cold weather alert – and says vulnerable people should heat their homes to at least 18C, wear extra layers of clothing, and eat hot food to protect themselves.
But about 710,000 households cannot afford to follow this advice because they cannot pay for warm clothing, heating and food, and another 2.5 million families on low incomes are going without.
The research was carried out by the Joseph Rowntree Foundation, and its senior economist Rachelle Earwaker said: “The dangerously cold weather on the horizon is cause for concern.
The Met Office has extended yellow weather warnings into Thursday and Friday, with ice expected in much of Northern Ireland, Wales, parts of northern England and most of England’s eastern and western coastal areas.
The northern half of Scotland is likely to see snow and ice on both days, the forecaster said.
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