The north and south of Tenerife similarly have different climatic characteristics because of the rain shadow effect. The windward northwestern side of the island receives 73 percent of all precipitation on the island, and the relative humidity of the air is superior and the insolation inferior. The pluviometric maximums are registered on the windward side at an average altitude of between , almost exclusively in the La Orotava mountain range. Although climatic differences in rainfall and sunshine on the island exist, overall annual precipitation is low and the summer months from May to September are normally completely dry. Rainfall, similarly to that of Southern California, can also be extremely erratic from one year to another.