Owing to its location in the Dahomey Gap, where the coast runs parallel to the prevailing moist monsoonal winds, Accra features a very marginal hot semi-arid climate (Köppen climate classification: BSh) that borders on a tropical wet and dry climate (Köppen climate classification: Aw). The average annual rainfall is about 730 mm, which falls primarily during Ghana's two rainy seasons. The chief rainy season begins in April and ends in mid-July, whilst a weaker second rainy season occurs in October. Rain usually falls in short intensive storms and causes local flooding in which drainage channels are obstructed.