Weather in the Olympic Mountains

Driest weather in the state

Sequim receives less than 15” of rain a year, since it lies within the rain shadow of the Olympic Mountains. That’s equivalent to the annual rainfall in Los Angeles, CA! That means that even though we’re next door neighbors with some of the wettest temperate rainforests in the United States, Sequim has some of the driest weather in Washington State. We also benefit from cool breezes blowing in off the Strait of Juan De Fuca, providing some extra humidity in spite of the low rate of precipitation. This combination of unique weather systems makes Sequim’s climate unique, comfortable, and desirable!

 

How does a rain shadow work? In short, the rain shadow effect is created by strong, wet winds blowing in from the Pacific. These winds are deflected by the mountains and forced upwards. As the winds climb they are cooled and the vast majority of the water vapor the winds carry is condensed and released in the form of rain or snow. As the wind makes its way back down the mountains, and towards Sequim, the wind becomes warmer during it’s descent causing remaining water droplets to evaporate back to water vapor and carried over Sequim resulting in low rainfall creating the ‘Blue Hole.’

So what is a rain shadow, and how is it created? The Olympic Mountains create a natural barrier from the strong, wet Pacific winds that can batter our coastline. The mountains deflect the eastward winds, forcing them upwards, which cools and condenses the water vapor to create rain and snow at higher altitudes. As the winds continue over the Olympic peaks and down towards our valley, they warm again, causing much of the remaining water vapor to evaporate. That gives Sequim clearer skies than the nearby rainforests, and earned our town’s nickname “The Blue Hole”.