The rainy season, or monsoon season, is the time of year when most of a region's average annual rainfall occurs.

Under the Köppen climate classification, for tropical climates, a wet season month is defined as a month where average precipitation is 60 millimetres (2.4 in) or more.[4] In contrast to areas with savanna climates and monsoon regimes, Mediterranean climates have wet winters and dry summers. Dry and rainy months are characteristic of tropical seasonal forests: in contrast to tropical rainforests, which do not have dry or wet seasons, since their rainfall is equally distributed throughout the year.[5] Some areas with pronounced rainy seasons will see a break in rainfall mid-season, when the intertropical convergence zone or monsoon trough moves to higher latitudes in the middle of the warm season