The climate varies regionally. The low-lying Fergana Valley in the southwest is subtropical and extremely hot in summer, with temperatures reaching The northern foothills are temperate and the Tian Shan varies from dry continental to polar climate, depending on elevation. In the coldest areas temperatures are sub-zero for around 40 days in winter, and even some desert areas experience constant snowfall in this period. In the lowlands the temperature ranges from around in January to in July.