Variations in altitude in Malawi lead to wide differences in climate. The vast water surface of Lake Malawi 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. 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).