The climate varies widely depending on the elevation. The southern part of Bhutan is tropical with temperature 15 degree in winter to 30 degree in summer, and eastern region of the country is warmer than the central valleys. The central valleys of Punakha, Wangduephodrang, Mongar, Tashigang and Lhuentse have semi-tropical climate with cool winters, while Paro, Thimphu, Tongsa and Bumthang have a much harsher climate, with summer monsoon rains and winter snowfall. Winter in Bhutan starts from mid-November till mid-March, dry and sunny for the most part, with temperatures around 15 degree C in the daytime and below zero degree at night. The monsoon usually arrives in mid-June, with light rain in the afternoon and evening.