Which climate conditions allow tropical rainforests to grow?

Tropical rainforests thrive in specific climatic conditions characterized by consistent warmth and high moisture levels. The primary requirements for their growth include:

• Temperature: These regions maintain high mean temperatures, typically between 20 and 29 °C (68 and 84 °F), with no month falling below 18 °C (64 °F). The equatorial latitude ensures that day length and temperatures remain fairly constant throughout the year.1
• Rainfall: Tropical rainforests require significant annual precipitation, generally exceeding 1,800 to 2,500 mm (about 70 to 100 inches), which should be distributed relatively evenly across the year.12
• Humidity: The environment is marked by high atmospheric humidity, which often exceeds 50 percent during the day and approaches 100 percent at night.1

While these conditions are standard, local variations in topography—such as the orientation of coastlines relative to prevailing winds—can influence rainfall patterns and restrict or support rainforest distribution within the tropics. Additionally, as altitude increases, temperatures decrease, eventually leading to the transition from lowland rainforests to montane forests.12