Variations in altitude in Malawi lead to wide differences in climate. The vast water surface of Lake Niassa has a cooling effect, but because of the low elevation, the margins of the lake have long hot seasons and high humidity, with a mean annual temperature of 24° C (75° F ). Precipitation is heaviest along the northern coast of Lake Malawi, where the average is more than 163 cm (64 in) per year; about 70% of the country averages about 75–100 cm (30–40 in) annually. In general, the seasons may be divided into the cool (May to mid-August); the hot (mid-August to November); the rainy (November to April), with rains continuing longer in the northern and eastern mountains; and the post-rainy (April to May), with temperatures falling in May. Lilongwe, in central Malawi, at an elevation of 1,041 m (3,415 ft), has a moderately warm climate with adequate rainfall. The average daily minimum and maximum temperatures in November, the hottest month, are 17° C (63° F ) and 29° C (84° F ), respectively; those in July, the coolest month, are 7° C (45° F ) and 23° C (73° F ).