How Can a Rainforest Receiving 2,500mm of Annual Rain Dry Out? The Threat to Monteverde

MONTEVERDE, Costa Rica — In Monteverde, it rains heavily—over 2,500mm annually. Yet, scientists warn that rising cloud decks and loss of fog are causing this famed cloud forest to dry out from within.

Horizontal Precipitation: The Missing Piece of the Water Cycle

In cloud forests, water arrives not only as rain, but as fog intercepted by canopy plants (epiphytes). These epiphytes—representing nearly 30% of local flora—act as sponges that trap and slowly release moisture.

“Although annual precipitation remains similar, the amount of moisture retained by canopy plants is drastically decreasing.”

— Dr. Alexander Rojas, UNA

Why Cloud Forests Are Drying Despite Rain

• Rising Cloud Decks: Warming temperatures force clouds higher, passing over the forest canopy without touching vegetation.
• Direct Sunlight: Reduced fog cover exposes mosses and epiphytes to higher solar radiation, speeding up evaporation.
• Wind & El Niño: Stronger trade winds strip moisture directly off tree leaves.