The geographical location and surface features are the two most important factors determining the climate of Poland. The climate has transitional character between maritime and continental. Winters are white and beautiful, whereas summers tend to be hot and dry, pleasent and full of sunshine. Spring starts in March with temperatures varying from -1 to +20 °C, until about April or May. July is the hottest month, but the rest of the summer is also quite warm with temperatures from 21 to 32 °C. Initially warm September is the beginning of Poland's autumn. Thereafter, days become colder until December, when winter begins and the temperature drops from a few degrees below zero to sometimes even - 20 °C. Winter lasts from December to March and includes shorter or longer period of snow. In the high mountains snow lies till May.