Owing to Somalia's proximity to the equator, there is not much seasonal variation in its climate. Hot conditions prevail year-round along with periodic monsoon winds and irregular rainfall. Mean daily maximum temperatures range from , except at higher elevations along the eastern seaboard, where the effects of a cold offshore current can be felt. In Mogadishu, for instance, average afternoon highs range from  in April. Some of the highest mean annual temperatures in the world have been recorded in the country; Berbera on the northwestern coast has an afternoon high that averages more than  from June through September. Nationally, mean daily minimums usually vary from about . The greatest range in climate occurs in northern Somalia, where temperatures sometimes surpass  in July on the littoral plains and drop below the freezing point during December in the highlands. In this region, relative humidity ranges from about 40% in the mid-afternoon to 85% at night, changing somewhat according to the season. Unlike the climates of most other countries at this latitude, conditions in Somalia range from arid in the northeastern and central regions to semiarid in the northwest and south. In the northeast, annual rainfall is less than ; in the central plateaus, it is about . The northwestern and southwestern parts of the nation, however, receive considerably more rain, with an average of  falling per year. Although the coastal regions are hot and humid throughout the year, the hinterland is typically dry and hot.