Istanbul has four distinct seasons. The winter months (December to February) are cold and rainy, and the city is known to get snow that can sometimes be heavy enough to justify schools being closed. Spring, beginning in March, can be exceptionally wet, but it also brings a riot of colour as flowers bloom throughout the city. June ushers in summer, which is hot and humid enough to make an air conditioner extremely useful during this time of the year. Autumn in Istanbul, from September to November, is mild.