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Seattle’s canopy cover is ~28%, whereas New York City’s urban forest covers ~22% of its total landscape. Hence, ‘Emerald City’ is a befitting moniker for Seattle. But what about ‘Rain City?’ Meteorologists say Seattle has 2 seasons: wet and dry. So, why does it rain so much in Seattle?
It rains so much in Seattle because the moisture-laden warm air currents from the Pacific Ocean are forced upward by the Olympic Mountains to the west of the city. This causes condensation and, subsequently, precipitation on the slopes and beyond in the Northwest.
However, Seattle is not the only city that receives abundant rain, whether it is by the number of days in a year or total precipitation. You may be wondering now about how much rain Seattle gets and if it is the rainiest city in the U.S. Read on as I explain the facts about our Rain City.
Is Seattle the U.S.’s Rainiest City?
Seattle is not the U.S.’s rainiest city. In fact, Seattle isn’t even among the top 5 rainiest cities or regions in the country if I go by the total annual precipitation. However, if I use the parameter of the total number of days when it rains in Seattle, the city is among the top 5 wettest places in the U.S.
Seattle Is Not Among the Top 5 Rainiest Cities in the U.S.
Here are the top 5 rainiest or wettest cities in the U.S. by total precipitation (only rainfall, excl. snow):
- New Orleans: 60 to 66 inches (152 to 168 cm)
- Miami: 56 to 70 inches (142 to 178 cm)
- Birmingham: ~56 inches (142 cm)
- Memphis: ~55 inches (140 cm)
- Jacksonville: ~54 inches (137 cm)
New York City receives ~52 inches (132 cm) of rainfall annually, which places it in the top 10 every year. The exact rank varies because a few other cities compete with very little difference among their annual precipitations, such as:
The total annual precipitation parameter places Seattle beyond the first 30 spots. The rank does change because the total yearly precipitation varies quite a bit in Seattle. Also, the citywide and metropolitan region average doesn’t accurately reflect the variance among the weather stations.
For instance, here are 3 normal precipitation levels at as many weather stations in Seattle:
- Seattle Boeing Field: 36 inches (91.4 cm)
- Seattle Sand Point: 39 inches (99 cm)
- Seattle-Tacoma Airport: 42 inches (106.7 cm)
Seattle Is Among the Top 5 Cities in the U.S. With the Most Days of Rain
Here are the top 5 cities and metropolitan regions in the U.S. with the most days of rain:
- Buffalo: ~167 days
- Portland: ~164 days
- Cleveland: ~155 days
- Pittsburgh: ~151 days
- Seattle: ~150 days
Of course, Seattle displaces Pittsburgh and also Cleveland sometimes if it receives rain on a few more days than usual. But 150 is the average as per the normal annual precipitation over the years.
How Much Rain Does Seattle Get in a Year
Here’s how much rain the Seattle City Area received annually from 2000 to 2022:
|Year||Total Annual Precipitation|
|2000||28.76 inches (73 cm)|
|2001||36.82 inches (93.5 cm)|
|2002||28.42 inches (72.2 cm)|
|2003||Annual data not available|
|2004||31.21 inches (79.3 cm)|
|2005||34.53 inches (87.7 cm)|
|2006||45.05 inches (114.43 cm)|
|2007||31.83 inches (80.85 cm)|
|2008||30.46 inches (77.4 cm)|
|2009||35.75 inches (90.8 cm)|
|2010||42.57 inches (108.13 cm)|
|2011||34.25 inches (87 cm)|
|2012||46.91 inches (119.15 cm)|
|2013||29.76 inches (75.6 cm)|
|2014||46.77 inches (118.8 cm)|
|2015||39.35 inches (99.95 cm)|
|2016||45.03 inches (114.4 cm)|
|2017||44.83 inches (113.87 cm)|
|2018||37.26 inches (94.64 cm)|
|2019||31.27 inches (79.42 cm)|
|2020||44.57 inches (113.21 cm)|
|2021||40.00 inches (101.6 cm)|
|2022||Annual data not available|
The total annual precipitation in Seattle isn’t high by any standards, and I am not comparing this data with the equatorial regions or the tropics that receive much more rain. Many rainy places in the world receive a lot more rain than Seattle or the wettest cities in the U.S.
For instance, the Indian state of Meghalaya has a village called Mawsynram that receives ~467 inches (1,186.18 cm) of rain every year. However, Seattle has a different story because of the almost relentless rain for days, weeks, and often months.
The incessant rain in Seattle isn’t a downpour that some people may imagine. Most of what is rain in Seattle is essentially a drizzle or a sprinkle. Showers and thunderstorms aren’t atypical in the city, but there are a few distinct attributes about Seattle rain that many may find quaint.
Consider the reality of virga. Seattle residents are all too familiar with what many like to refer to as mist. This mist is not rain or distant fog, technically. Virga is a phenomenon when trails of precipitation fall from a cloud’s underside, but the water evaporates before reaching the ground.
Seattle has a mist problem, usually in the mornings. Drizzles may last days and often weeks. A sprinkle-rain can last months during some wet spells. Add to that the occasional and surprising downpours. A heavy downpour doesn’t last long, but its abrupt arrival isn’t always a pleasure.
Add to these elements the fact that Seattle receives rainfall for around 150 days a year. There is an official wet season from October through March. But it is rare for any month to have not even one rainy day in Seattle, which is by its standards, of course.
This perpetual state of rainfall with cloudy and overcast conditions for most of the year has helped Seattle bag the infamous #1 spot on the Dreariness Index. But the city has company, with Buffalo tied at the top with Seattle as the two gloomiest cities in the U.S.
The Reason Why It Rains So Much in Seattle, Yet Not Really
There are a few geographical factors due to which it apparently rains so much in Seattle. Here’s what happens along the coastal Pacific Northwest:
- The Pacific Northwest’s oceanic currents carry warm air northward from the equator and eastward in a clockwise circulation.
- These warm currents pick up a lot of moisture from the Pacific Ocean and are heavily loaded when they reach the Olympic Mountains.
- Although the Olympic Mountains aren’t very tall, the surface currents loaded with vapor move upward, causing condensation and forming clouds.
- These clouds cause a lot of precipitation along the coast and the western slopes and valleys of the Olympic Range, up to 170 inches (432 cm).
- Having lost significant moisture, drier surface currents descend over Puget Sound and create the typical overcast conditions in Seattle.
- Seattle has 58.67 sq mi (152 sq km) of water of its total 142.5 sq mi (369.2 sq km) city area, which is a little over 41%.
- Also, Seattle is surrounded by water, including lakes and the ocean, due to its location on an isthmus.
- All these factors lead to a persistent cycle of evaporation, condensation, cloud formation, and precipitation.
Therefore, Seattle has a long wet season, and rainfall isn’t uncommon during the drier months, either. But the quantum of daily or even annual rainfall isn’t high, except for thunderstorms and tornadoes.
If you’re into precipitation patterns, you should check out my article on rainfall time in California. I’ve also elaborated on how much rainfall you get in California broken down by months. [When Does It Rain in California?]
Seattle is one of the rainiest cities in the U.S. by the total number of days the city receives some rain. But the city doesn’t receive as much rain as New Orleans, Miami, Birmingham, Memphis, or Jacksonville. Still, Seattle remains one of the dreariest U.S. cities, along with Buffalo.