Wet season

Lore & Background

Under the Köppen climate classification, a wet season month is defined as one where average precipitation is 60 millimetres or more. In contrast to tropical rainforests, which have rainfall evenly distributed throughout the year, tropical seasonal forests have distinct dry and rainy months. Some areas with pronounced rainy seasons experience a break in rainfall mid-season when the Intertropical Convergence Zone or monsoon trough moves to higher latitudes. Most places have only one wet season, but areas of the tropics can have two, as the monsoon trough may pass over locations twice per year.

Reader's Guide

The wet season has profound significance for both natural systems and human societies. In tropical areas, it improves air quality, freshens water, and spurs substantial vegetation growth, leading to crop yields later in the season. However, it also brings challenges: rivers overflow, soil nutrients diminish, erosion increases, and the incidence of malaria and dengue rises where high temperatures coincide with rainfall. The wet season is a time of food shortages before crops mature, causing seasonal weight changes in developing countries. Floods can be exacerbated by fires from the previous dry season, which make soils hydrophobic. Governments help manage these risks through flood plain mapping and erosion control outreach. The wet season is known by many local names, such as 'storm season' in Mexico and 'Gudjewg' among First Nations of Northern Australia, reflecting its varied cultural and environmental impacts.

Did You Know?

• The wet season is sometimes called the 'green season' as a euphemism by tourist authorities.
• In the wet season, rainfall mainly occurs in late afternoon and early evening in savanna and monsoon regions.
• The wet season in the Negev Desert of Israel extends from October through May.
• Cows calve at the beginning of the wet season.