Shanghai has a humid subtropical climate and experiences four distinct seasons. Winters are chilly and damp, and cold northwesterly winds from Siberia can cause nighttime temperatures to drop below freezing, although most years there are only one or two days of snowfall. Summers are hot and humid, with an average of 8.7 days exceeding 35 °C (95 °F) annually; occasional downpours or freak thunderstorms can be expected. The city averages 4.2 °C (39.6 °F) in January and 27.9 °C (82.2 °F) in July, for an annual mean of 16.1 °C (61.0 °F).