In many parts of the tropics, high temperatures and heavy rainfall are accompanied by very humid and often cloudy conditions. Winds are usually light but tropical storms including hurricanes (cyclones) can be a problem. Equatorial (A1) climates are wet all year with rainfall fairly evenly distributed. The sun is nearly overhead so it is evenly hot all year. They are usually between 5 degrees of latitude north and south of the equator. Further north and south, between 5 and 15 degrees north and south of the equator, there is a distinct wet and dry season with wet summers and dry winters and still very high temperatures all year round.

Conditions here are perfect for the growth of lush tropical rainforest and the greatest rainforests in the world lie within 10 degrees latitude of the equator. The most well known are the Amazon rainforest of Brazil, the Congo basin of Central Africa and the jungles of Malaysia, Indonesia, Burma and Vietnam. Humans are slowly destroying much of these environments and perhaps upsetting the world's climatic equilibrium.

In many areas of tropical climates, such as in East Africa, a vegetation known as savannah is characteristic. Vegetation in these areas must be able to survive months of drought and lots of plant life is dormant during these times, springing quickly into life with the onset of the rains.

In parts of south and southeast Asia the contrast between the wet and dry seasons is so marked that they are called tropical monsoon (A2) climates. Monsoon climates are caused mainly by temperature differences between land and sea. In these areas, the prevailing winds reverse their direction twice a year. This divides the year into a hot wet season followed by a mainly warm dry one. The best known monsoon affects the Indian subcontinent. During early summer, southwesterly winds carry warm moisture-laden air from the Indian Ocean. These winds bring the heavy monsoon rains known as the southwest monsoon. Then in winter, the winds reverse direction. Cool dry winds blow from the northeast towards the equator lowering temperatures. The torrential monsoon rains often cause flooding.