Altitude and relief greatly affect both temperature and rainfall in Zimbabwe. The higher areas in the east and the highveld receive more rainfall and are cooler than the lower areas. Temperatures on the highveld vary from 12–13°c (54–55°f) in winter to 24°c (75°f) in summer. On the lowveld the temperatures are usually 6°c (11°f) higher, and summer temperatures in the Zambezi and Limpopo valleys average between 32–38°c (90–100°f). The eastern mountains receive more than 100 cm (40 in) annually, while Harare has 81 cm (32 in) and Bulawayo 61 cm (24 in). The south and southwest receive little rainfall. Seasonal shortages of water are common. The summer rainy season lasts from November to March. It is followed by a transitional season, during which both rainfall and temperatures decrease. The cool, dry season follows, lasting from mid-May to mid-August. Finally, there is the warm, dry season, which lasts until the onset of the rains.