Africa's climatic zones are largely controlled by the continent's location astride the equator and its almost symmetrical extensions into the Northern and Southern Hemispheres. Thus, except where altitude exerts a moderating influence on temperature or precipitation (permanently snowcapped peaks are found near the equator), Africa may be divided into six general climatic regions. Areas near the equator and on the windward shores of SE Madagascar have a tropical rain forest climate, with heavy rain and high temperatures throughout the year. North and south of the rain forest are belts of tropical savanna climate, with high temperatures all year and a seasonal distribution of rain during the summer season. The savanna grades poleward in both hemispheres into a region of semiarid steppe (with limited summer rain) and then into the arid conditions of the extensive Sahara (north) and the Kalahari (south). Belts of semiarid steppe with limited winter rain occur on the poleward sides of the desert regions. At the northern and southern extremities of the continent are narrow belts of Mediterranean-type climate with subtropical temperatures and a concentration of rainfall mostly in the autumn and winter months.