Weather Blog

What makes a rain forest?

What makes a rain forest?
Sure, it's been sunny since the start of the month, so what better topic than how rain forests are formed? A rain forest generally needs two ingredients -- a moist airflow and some mountainous terrain. In the Olympic Rain Forest's case, our general weather pattern features a constant west or southwest flow off the Pacific Ocean. That of course, carries a lot of moisture along from being over the ocean for thousands of miles.

As that flow hits the west and southwest side of the Olympics, the terrain forces the air upward. As air rises, it cools and condenses, squeezing out its abundant moisture and soon, you've got a rain forest. The Olympic rain forests gets over 200 inches of rain a year and is the wettest location in the lower 48 states.

Hawaii has abundant rain forests from the tropical trade winds running into their mountains, and South America has gobs of rain forests from moist flow running into the Andes Mountains.