Which climate zone is characterized by heavy rainfall and high humidity year-round?

The tropical rainforest climate is characterized by heavy rainfall and high humidity throughout the year. This climate zone typically experiences annual precipitation that exceeds 2000 millimeters (about 79 inches), with rain occurring in nearly all months, and humidity levels that can frequently reach 80% or higher.

The abundance of rainfall combined with warm temperatures creates ideal conditions for thick, lush vegetation and diverse ecosystems, often referred to as rainforests. These regions are home to a vast number of plant and animal species, making them some of the most biodiverse areas on the planet.

In contrast, the other climate zones do not share the same characteristics of consistently high rainfall and humidity. Tundra climates are cold, with short summers and low precipitation. Desert climates are defined by their arid conditions and minimal rainfall. Temperate climates have more varied weather patterns, with distinct seasons, including a specific rainy season but not the year-round consistent heavy rainfall found in tropical rainforests. This makes the tropical rainforest climate the clear answer for the condition described in the question.