Tunis has a hot-summer Mediterranean climate , characterized by hot and dry, prolonged summers and mild winters with moderate rainfall. The local climate is also affected somewhat by the latitude of the city, the moderating influence of the Mediterranean sea and the terrain of the hills.
Winter is the wettest season of the year, when more than a third of the annual rainfall falls during this period, raining on average every two or three days. The sun may still increase the temperature from 7 °C (45 °F) in the morning to 16 °C (61 °F) in the afternoon on average during the winter. Frosts are rare. In spring, rainfall declines by half. The sunshine becomes dominant in May when it reaches 10 hours a day on average. In March temperatures may vary between 8 °C (46 °F) and 18 °C (64 °F), and between 13 °C (55 °F) and 24 °C (75 °F) in May. However, it is common for temperatures to soar even as early as April with record temperatures reaching 40 °C (104 °F). In summer, rain is almost completely absent and the sunlight is at a maximum. The average temperatures in the summer months of June, July, August, and September are very high. Sea breezes may mitigate the heat, but sometimes the sirocco winds reverse the trend. In autumn, it begins to rain, often with short thunderstorms, which can sometimes cause flash floods or even flood some parts of the city. The month of November marks a break in the general heat with average temperatures ranging from 11 °C (52 °F) to 20 °C (68 °F).