Extreme temperatures during both seasons are moderated by the prevailing northerly winds. In the coastal region, average annual temperatures range from a high of 37° C (99° F) to a low of 14° C (57° F). Wide temperature variations occur in deserts, ranging from a high of 46° C (114° F) during daylight hours to a low of 6° C (42° F) after sunset. During the winter season desert temperatures often drop to 0°C (32°F). The most humid area is along the Mediterranean coast, where the average annual rainfall is around 200 mm. Precipitation decreases rapidly in the south; Cairo receives on average only 26 mm (1 inch) of rain per year, and in many desert locations it may rain only once in more than one year