Wintersmith - (Discworld Novel 35)

When Tiffany Aching - young witch - steps into a dance she shouldn't, the spirit of winter falls in love with her. He gives her roses and icebergs, says it with avalanches and showers her with snowflakes - and suddenly winter is all around her. All the time. With the help of the Nac Mac Feegle, first met in The Wee Free Men, and a bit of advice from witches Granny Weatherwax and Nanny Ogg, Tiffany must put the mess right - or there will never be another springtime ...