Wet season

The wet season (sometimes called the rainy season or monsoon season) is the time of year when most of a region's average annual rainfall occurs. Generally, the season lasts at least one month. Areas with wet seasons are found in parts of the tropics and subtropics.

When the wet season happens during warm weather or summer, precipitation usually falls in the late afternoon and early evening. During this time, air quality gets better, fresh water quality improves, and vegetation grows a lot, which helps crops. However, rivers may overflow, and some animals move to higher ground. While this season brings growth, it can also increase diseases like malaria and dengue in warm tropical areas.

Plants like cassava, maize, rice, and yam do well when planted during the wet season. The wet season is very important for farming and nature, even though it can bring challenges too.

Character of the rainfall

In places where heavy rain comes with a change in wind, the wet season is called the monsoon season. Many warm climates far from the poles see this kind of rainy weather. The rain happens mostly because the ground heats up during the day, creating storms. This means rain usually falls in the late afternoon and early evening in areas like grasslands and monsoon regions.

A lot of the rain falls right at the start of a storm, before it fully develops. Most places have just one wet season each year. But in some tropical areas, there can be two wet seasons because a special weather pattern moves over them twice a year. However, rain forests get rain spread out evenly all year, so they don’t have a wet season.

Areas affected

Many places around the world have a special time of year when it rains a lot. In areas with a savanna climate in Sub-Saharan Africa, such as Ghana, Burkina Faso, Darfur, Eritrea, Ethiopia, and Botswana, there is a clear rainy season. Subtropical areas like Florida, South and Southeast Texas, and southern Louisiana in the United States also have a rainy season.

Monsoon regions include the Indian subcontinent, Southeast Asia (including Indonesia and the Philippines), northern parts of Australia, Polynesia, Central America, western and southern Mexico, the Desert Southwest of the United States, southern Guyana, and northeast Brazil.

Some places have two wet seasons. Northern Guyana has one in early spring and another in early winter. In western Africa, southern areas have two rainy seasons, but northern areas have only one. In places with a Mediterranean climate, such as the west coast of the United States, southwest coast of Australia and South Africa, and parts of Italy, Spain, Greece, and more, the wet season happens in the winter months. The Negev Desert of Israel has its wet season from October through May. The Sonoran Desert experiences wet seasons from both the Mediterranean and monsoon climates.

The wet season has many different names around the world. In Mexico, it is called the "storm season". In Northern Australia, the wet season from December to March is called Gudjewg, a term that refers to the strong storms, flooding, and plant growth that occur during this time.

Effects

In tropical areas, when the rainy season begins, daytime temperatures become cooler and nighttime temperatures become warmer, making the daily temperature changes smaller. Heavy rain and winds, like in Hong Kong, can help clear the air and improve its quality.

In places like Brazil, the rainy season changes wind patterns over the ocean. Rainwater helps balance the chemistry of nearby water and makes it softer by washing away minerals. Heavy rain can also cause soil to wash away, enriching nearby oceans but sometimes leading to flooding.

Floods

Lots of rain can cause big floods, especially in mountains where landslides and mudflows can happen. Rivers may overflow, flooding homes and damaging crops, like along the Ghaggar-Hakra River in India. Fires from the dry season can make soil repel water, making floods worse. Governments help by mapping flood-prone areas and giving advice on how to protect land from erosion.

Life adaptations

Humans

The wet season is when plants grow a lot in places with Savanna climates. But it can also be a time when food is scarce before crops are ready to harvest. This can cause people in some countries to lose weight during the wet season until they can eat the new crops. Also, diseases like malaria become more common when it is very hot and rainy.

Animals

Cows usually have their babies at the start of the wet season. When the rainy season begins, monarch butterflies leave Mexico. Some tropical butterflies have bigger spots on their wings during this time to stay safe from animals that might hurt them. They are also more active in the wet season than in the dry season. In warm areas, more crocodiles lay eggs when the rain comes because the water near the shore becomes less salty. Other animals, like arroyo toads, lay eggs a few months after it rains. Armadillos and rattlesnakes move to higher ground.