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Why Does It Rain So Much In Seattle?

Aug 16th, 2021

Seattle is known as a rainy, gray place, but it turns out that it’s by no means the rainiest place in Washington, or even in the nation! If you live in our luxury Seattle apartments, then here’s a little bit about Seattle’s rainy reputation and the forces that make the weather the way that it is!

Does it actually rain more in Seattle?

Seattle is known for being a rainy city. It seems that any movie or TV show set in the Emerald City has the obligatory rainy day stereotype built into the story, and there’s always someone with an umbrella running through the damp streets. 

And yes, there’s some truth to the stereotype, but not to quite the extent as we’ve been led to believe. Seattle does have rain, sure, but there are also plenty of gorgeous, sunny days that make Mount Rainier pop in the horizon. To get a better idea of how rainy Seattle really is, let’s put it all into some perspective. 

Seattle has an average of 149 rainy days each year, meaning that there were about 149 days where over 0.01 inches of rain fell over the course of the day. On the other side of the country, Miami gets about 135 rainy days per year, and New Orleans gets about 115. Las Vegas only gets about 27 rainy days per year, which is toward the lowest end of the spectrum, while Juneau, Alaska, gets a whopping 223 days! 

When we look at a city’s raininess (that’s a scientific term, right?), though, there’s more to take into account than just how many days of precipitation the place gets. Miami, for example, gets fewer rainy days than Seattle does, but it gets far more rain overall! Seattle’s average annual rainfall comes out to around 37.7 inches over those 149 days, whereas Miami gets around 61.9 inches over its 135 days. When it does rain in Miami, it rains harder and longer thanks to the heavy thunderstorms and hurricanes, resulting in a higher average rainfall each year. 

Rainfall varies wildly depending on the geographical surroundings and location along certain wind streams. Up in Juneau, around 54 inches of rain falls over 223 days, while New Orleans gets 62.7 inches over just 115 days. Each city gets a different type of rain, too, depending on the moisture content and the amount of warm air, which we will get to in a second. 

Even nearby Portland gets more rainy days but less overall rain than Seattle does, and it’s just a few hours away!

All this to say that Seattle, while it is a rainy city, is not the rainiest of them all, contrary to popular belief. It is pretty interesting to learn what makes Seattle so unique when it comes to weather patterns, though, and a lot of it has to do with the nearby Olympic Mountains. 

What makes Seattle so rainy?

Seattle is located slap-bang in the middle of a convergence zone where nearby weather patterns meet. It’s here that different streams of hot air, cold air and moisture collide, forming clouds, rain, hail and snow. 

Weather conditions require a few ingredients to create the perfect storm, literally and figuratively. Rain is formed when warm, moist air rises and cools, where it condenses and falls as rain, snow or hail. This warm air can be forced upwards by either cold air streams or changes in elevation, and thanks to a handy set of mountain ranges, the Puget Sound has both!

If we look at a map of the Puget Sound, we can see that there are a few mountain ranges that surround the water: the Olympic Mountains, the Cascade Range and the Vancouver Island Ranges. 

Warm, moist air blows eastward from the Pacific Ocean and hits the Washington coastline, where places like Tahola, Forks and Quillayute are on the receiving end of all the stormy weather. It’s not uncommon for towns right on the coast to receive around a hundred inches’ worth of rain each year, since nothing is there to impede the ocean-borne air currents. 

These warm air currents soon hit the Olympic Mountains, where the air rises quickly and the condensation squeezes any moisture out. The rainforests on this side of the peninsula are there as a direct result of all that moisture pouring out of the cooling air, and whatever moisture is left falls as snow at the higher elevations. 

The air that makes it to the other side of the mountains is, by that point, devoid of water vapor, and it sinks to the lower elevations as warm, dry air. The area covered by this warm air is called a rain shadow, as the mountains have effectively wrung out any water vapor and moisture the air might have once had. This rain shadow covers areas like Sequim and Port Gamble, and even sometimes as far out as Oak Harbor and Bremerton! 

The Olympics also split the air currents around the mountains, sending bands of warm air north and south around the peninsula. The Vancouver Island Mountain Range directs the air through the Strait of Juan de Fuca into the Puget Sound, and the Cascades direct its band of air north toward the sound, too. Coupled with a stream of cold air that blows south from the Fraser River Valley, all these bands of warm, cold, wet and dry air converge right near Everett and both King and Snohomish counties. This area of convergence forces the air to rise yet again, where it turns into clouds and creates stormy weather. The Cascade Range blocks the weather from travelling east, trapping the rain and storms on the west side. 

These weather patterns result in stratiform rain, which is that thin, mist-like rain that can cover miles of ground. Convection rain is made up of large droplets that form as wind and rising air forces water droplets to clump together, and it's the type of rain that the Olympic rainforests get before the mountains block all that, too. 

So, thanks to the Olympic Mountains, Seattle ends up with the misty, rainy weather we have today! 

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Featured photo courtesy Pixabay/nikondian

Author of Article

Colleen Ford is a South African who now lives in Spokane, Washington. She loves to travel, camp (in warm weather) and bake.

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