Kentucky governor Andy Beshear on Sunday said at least 11 people were dead, with the number expected to increase.

Severe storms also swept through parts of Florida and Georgia, where tornado watches were in effect early on Sunday, the National Weather Service (NWS) said.

Elsewhere, bone-chilling cold is expected for the northern plains with low temperatures into the -30s F near the Canadian border. Dangerously cold wind chill temperatures in the Dakotas and Minnesota of -40F (-40C) to -50F are expected.

Heavy snowfall amounts were expected in parts of New England and northern New York. In some areas, wind gusts could reach 60mph (about 97km/h) and create “hazardous whiteout conditions”, the NWS said.