Zimbabwe lies wholly in the tropics - stretching from 15.5 to 22.5 degrees South latitude. The sun is overhead twice a year. The least angle of elevation of the sun is 45 degrees over the southernmost parts of the country. An important geographic landmark to the climate of Zimbabwe is the presence and position of Madagascar. The South-East trades originating from the subtropical anticyclone are not afforded a thorough flow to mainland Africa. They deviate northward over Madagascar but curve southward over the Mozambique Channel, then turn northward over mainland Africa. The southern hemisphere subtropical anticyclone and the Inter-tropical Convergence Zone (ITCZ) are the main features which influence weather in Zimbabwe. The weather is overall favourable throughout the year. The summer season is from November to April, when temperatures are moderate to high, accompanied by intermittent rainfall. Occasionally, airflow across Zimbabwe is relatively dry. In winter (May to September) temperatures are normally cool to moderate and there is typically little or no rainfall.