The countries with a predominantly equatorial climate are mainly those located within 5 to 10 degrees of latitude of the equator, according to Lord Wandsworth College. In these zones, day and night are both 12 hours long, and the annual temperature range is very narrow. Steady temperatures and high precipitation make the equatorial zone home to the tropical rainforest climate that promotes plant growth.
Countries that have tropical rainforest climates straddle the equator in South America, Asia and Africa. According to Wikipedia, the African countries in this zone include the Democratic Republic of Congo, Uganda and Comoros. Some of the Central and South American countries with equatorial climates are Colombia, Brazil, Venezuela, Nicaragua, Panama, Guyana, Suriname and Peru. Indonesia has a similar climate, as do Vietnam, Malaysia and Sri Lanka.
Sometimes, local conditions conspire to create a tropical climate outside of the equatorial belt. This usually happens in warm regions that are close enough to the sea to receive a large amount of annual rainfall. According to Wikipedia, both Fort Lauderdale, Florida, and Hilo, Hawaii, have local climates that can be described as equatorial, even though both of these cities lie well outside the tropics in northern, more temperate, latitudes.