The tornadoes follow a month after fierce snowstorms swept through the US, leaving more than nine dead, cutting off power supplies and causing hundreds of road accidents. Flights had to be cancelled across a wide area, and tens of thousands of people were left without electricity. In Texas, a blizzard caused 50 vehicles to plough into one another on one stretch of motorway.

EUROPE

Europe lived through a bitterly cold winter in December, with snow leaving thousands stranded at airports, on mountain roads and in remote villages. Authorities in northeastern Bulgaria declared a state of emergency. The Mont-Blanc tunnel linking France and Italy had to be closed to trucks because sharp temperature differences between the two sides threatened to disrupt the tunnel's ventilation.