The climate of Egypt is characterized by a hot season from May to September and a cool season from November to March. Extreme temperatures during both seasons are moderated by the prevailing northern winds. In the coastal regions average annual temperatures range from a maximum of 37° C (99° F) to a minimum of 14° C (57° F). Wide variations of temperature occur in the deserts, ranging from a maximum of 46° C (114° F) during daylight hours to a minimum of 6° C (42° F) during the night. During the winter season desert nighttime temperatures often drop to 0° C (32° F). The most humid area is along the Mediterranean coast, where the average annual rainfall is about 200 mm (about 8 in). Precipitation decreases rapidly to the south; Cairo receives on average only 25 mm (1 in) of rain a year, and in many desert locations it may rain only once in several years.