Why do temperate rainforests often form near coasts and mountains?

Temperate rainforests often form near coasts and mountains because these geographical features are essential for generating the high levels of moisture required to sustain the biome.1

The primary mechanism for this is orographic precipitation. When moisture-laden air from the ocean encounters a mountain range, the topography forces the air to rise. As the air ascends, it cools, leading to the formation of clouds and significant precipitation on the windward slopes. This process ensures a consistent supply of moisture throughout the year, which is a defining characteristic of temperate rainforests.1234

Coastal proximity further supports these ecosystems by providing a steady source of humid, maritime air. In many regions, this moisture is supplemented by coastal fog, which provides additional water for lush plant growth even during periods of lower rainfall. Consequently, temperate rainforests are found primarily along western coasts where prevailing winds carry oceanic moisture toward mountainous terrain.14