UNI?O, MARANHAO

Tropical monsoon climate, occasionally also known as a tropical wet climate or tropical monsoon and trade-wind littoral climate in climate classification, is a relatively rare type of climate. Tropical monsoon climates have monthly mean temperatures above 18°C (64°F) in every month of the year and feature wet and dry seasons, as Tropical savanna climates do. Unlike tropical savanna climates however, a tropical monsoon climate's driest month sees less than 60 mm (2.36 in) of precipitation. Also a tropical monsoon climate tends to see less variance in temperatures during the course of the year than a tropical savanna climate. This climate has a driest month which nearly always occurs at or soon after the "winter" solstice for that side of the equator.

The Köppen Climate Classification subtype for this climate is "Am". (Tropical Monsoon Climate).

The average amount of precipitation for the year in União is 59.1" (1501.1 mm). The month with the most precipitation on average is April with 10.7" (271.8 mm) of precipitation. The month with the least precipitation on average is October with an average of 0.3" (7.6 mm).