The area receives about  of annual rainfall, which is concentrated from May through October with little or no precipitation the remainder of the year. The area has two main seasons. The wet humid summer runs from May to October when winds bring in tropical moisture from the sea, the wettest month being July. The cool sunny winter runs from November to April, when the air is relatively drier, the driest month being December. This season is subdivided into a cold winter period and a warm spring period. The cold period spans from November to February, when polar air masses push down from the north and keep the air fairly dry. The warm period extends from March to May when subtropical winds again dominate but do not yet carry enough moisture for rain to form.