The Puget Sound region is wedged between the Pacific and the Cascades...you'd think with all that rain (and snowmelt in the warmer months), there would be catastrophic flash flooding in lowland areas, of the magnitude seen in Oklahoma (1, 2, 3), Texas (1, 2, 3, 4) or Tennessee (1, 2, 3).

On the contrary, western WA is actually subject to droughts and wildfires, not something you'd expect from such a wet region with rainforests.

  • $\begingroup$ WA has a Rainforest? $\endgroup$
    – Tardy
    Commented Apr 22, 2021 at 21:43
  • 5
    $\begingroup$ en.wikipedia.org/wiki/Pacific_temperate_rainforests $\endgroup$ Commented Apr 22, 2021 at 21:46
  • $\begingroup$ I see, I didnt know sorry. $\endgroup$
    – Tardy
    Commented Apr 26, 2021 at 21:08
  • $\begingroup$ Western Washington is somewhat wet a lot of the time. Those other places are extremely wet for short periods of time. $\endgroup$
    – Vikki
    Commented Feb 2, 2022 at 16:57

6 Answers 6


Regarding climate, it does not rain in Seattle as much as people think; Seattle is in the snow shadow of the Olympic Mountains. It doesn't rain much in summer at all. Seattle gets rather dry in July and August.

Regarding flooding, the Skagit and Snohomish rivers north of Seattle flood regularly experience flooding. Some of the land in the flood plain is used for farming, and there are scattered households in the 100 year flood plain.

Regarding drought, drought severity is relative to the amount of precipitation and soil moisture levels typical for a specific locale. This means that even a rainforest can suffer drought. Because it's a relative concept, the rainfall during a drought in a rainforest would be a rainfall bonanza in arid climates.

Regarding forest fires, the Seattle area occasionally undergoes offshore flow. This occurs when the air pressure is lower in the Seattle area than it is east of the Cascades. This makes winds blow from the east, and if there's a forest fire east of the Cascades (which has a rather dry climate), that smoke can be carried westward toward the Seattle area by the offshore flow. That said, wildfires have occurred on the western slopes of the Cascades, and sometimes even in the temperate rainforest to the west of the Seattle area.

  • 19
    $\begingroup$ Another part of this is that much of the precipitation that Seattle receives is frequent small amounts, rather than multiple inches of rain all one time. Frequent small amounts are easier for the soil to absorb, reducing the chance of flash flooding. $\endgroup$ Commented Apr 23, 2021 at 12:13
  • 9
    $\begingroup$ Yes - the Seattle area tends to experience "mist with delusions of grandeur" - it will be wet/damp, without much actual rainfall. Which is why raincoats are popular compared to umbrellas. $\endgroup$ Commented Apr 23, 2021 at 15:38
  • 1
    $\begingroup$ too small of a change to edit, but: s/Snowhomish/Snohomish/ $\endgroup$
    – Cody
    Commented Apr 23, 2021 at 20:07
  • 2
    $\begingroup$ @Cody Thanks, fixed. $\endgroup$ Commented Apr 23, 2021 at 20:48
  • 4
    $\begingroup$ Yeah, people think of Seattle as being impossibly rainy, but the absolute amount isn't actually that astonishing; the problem is just that it drizzles down slowly ALL THE TIME. Also, the entire Seattle area is surprisingly steep, so the kind of flooding seen in flatter areas just doesn't happen; the water all drains into the sea where it belongs. $\endgroup$
    – Paul Z
    Commented Apr 24, 2021 at 16:44

Catastrophic flash flooding is usually a sign of poor city/road planning in flat areas or due to torrential downfall of rain. The reality is that all the terrain in Washington allows water to drain, rather than be left standing (which causes flash flooding). And let's be clear, it doesn't rain hard in WA very often, it's usually not torrential downpour, but rather a slow methodical drizzle that can easily drain away down rivers and streams. A lot of development in the mid-west ignores known flood plains.

As for your comment about wildfires, WA gets its rain in the cold seasons. So there is usually very dry weather in the summer when wildfires occur.

  • $\begingroup$ Seems harsh to blame city/road planning a lot of the time... many inches of rain in a day or hours is a lot to handle, after all many areas were once swampy from the same rain. A city could probably put inordinate amounts of money and space to giant drainage systems to cover every possible extreme scenario, or they could balance cost with utility, deal with occasional floods, and spend the money on other important things. And while building locations aren't perfect, msc.fema.gov/portal/home shows most cities try to do a fair job. But yeah, not so much a concern in Washington state :-D $\endgroup$ Commented Apr 25, 2021 at 23:57
  • 1
    $\begingroup$ "Catastrophic flash flooding is usually a sign of poor city/road planning" Or the converse, the lack of flooding is the result of good city planning. $\endgroup$
    – nick012000
    Commented Apr 26, 2021 at 1:51
  • 3
    $\begingroup$ it says "or" torrential downfall... it can flash flood anywhere with enough rain in a short time. $\endgroup$
    – f.thorpe
    Commented Apr 27, 2021 at 2:21

We do get flooding in the Puget Sound lowlands, but it actually happens most often when a mid-winter warm front brings a moderate amount of rain to higher elevations, causing sudden, extensive snowmelt.

Those weather systems, like one in February 2020 that caused quite a bit of flooding, suddenly raise temps by 15-20 degrees C (20-30 °F), and raise the snow/rain threshold up by 1000 meters (a few thousand feet) or more overnight. Even though the rainfall totals in those storms are usually not that great by comparison with the major storms in the South or the Plains, 5 cm/day (1-2 inches per day), the net effect is that a huge amount of water enters waterways all at once.

Even so, the steep slopes in the area generally mean that flooding is limited to a few river valleys. Our elevation profile goes from 3000 meters (8000 feet) to sea level in about 50 km (30 miles), so that water heads downhill FAST.

  • $\begingroup$ @Fred: I think °C ~ °F/1.8 or so, fortunately it's linear. But then it is not the anecdotal 15-20°, rather 11-16°. Can 16° really happen in a warmfront ? Imo we should really enforce using common units likely everywhere else in the world because others only cause errors. $\endgroup$
    – user22279
    Commented Apr 25, 2021 at 8:15
  • $\begingroup$ @Earthworm: I loath & detest non Metric units & wish they would go away! I was introduced to the British version of such units when I was young & lived through a 10 year transition period to the adoption of Metric units. I have no intention of going backwards. Unfortunately, some people still use obscure obsolete units, even in my country. I wish there was still a ban on using non Metric units, but that legislation had a sunset clause. In the 1980s television screen sizes were advertised in centimeters, they have since reverted back to inches, much to my chagrin. $\endgroup$
    – Fred
    Commented Apr 25, 2021 at 11:38
  • $\begingroup$ As to the numbers you mention in your comment, I simply put the original numbers back as a courtesy to the poster. I am simply adopting was has been discussed in the meta question: Is the imperial measurement system still used in the geosciences?. $\endgroup$
    – Fred
    Commented Apr 25, 2021 at 11:39
  • $\begingroup$ Would you consider the Feb 1996 floods in Portland to be similar? i.e. a dump of snow on the Cascade foothills followed by an atmospheric river, raising temperatures enough to melt the snow, which in turn results in extensive river flooding $\endgroup$ Commented Apr 7, 2022 at 0:20

To add some concrete data to some of the great answers already here:

Seattle is actually not particularly rainy, especially compared to other parts of WA, but also compared to other cities in the US. According to this chart of the largest 51 US cities, Seattle is wetter than 18, drier than 31, and tied with 1. Yet, Seattle only has less rainy-days than 5 cities, and more rainy-days than 45 cities. This indicates that Seattle probably gets its rain as a constant drizzle (which seems confirmed from anecdotal evidence) which would allow for the area to store and drain water faster than it peaks.

Interesting side-note:

A unexpected city that does suffer from flash floods is Tucson, Arizona. It receives 11.6 inches (294.6 mm) of rain yearly and 2.4 inches (61 mm) in its peak month. It is, however, flat and apparently large parts of the city do not have storm sewers. Additionally, the Arizona habitat does not seem to naturally drain water very well. This shows the importance both of city planning and natural drainage, which I'm sure Seattle, a wet city, has both in plenty.


Because soil drainage would be higher and the ground would take long to saturate Floods don't always happen in Rainy weather all the time because first the soil needs to be saturated (the point where it filled up with water) then the rain needs to continue, Flash floods are mostly produced this way.

So you would need lots of rain for a flood to occur in WA, I mean lots.


Because Washington has many river channels.The rivers of Western Washington flood almost every year. Snohomish, Skagit and other rivers flood, Seattle is largely spared, city knowing full well floods would be an issue for a city that supports rainforest ecosystem...........has drainage. Seattle is 53 meters (173 feet) above sea level and on mountainous terrain, so waters very seldom flood or inundate. Floods dominate flat terrain or valleys, which Seattle is Neither.........

  • $\begingroup$ the rainforest ecosystem is on the Olympic Peninsula, so you wouldn't get flow from it over in Seattle? $\endgroup$ Commented Feb 5, 2022 at 13:37
  • $\begingroup$ Seattle is 40 miles from Olympic Park.... $\endgroup$
    – LazyReader
    Commented Feb 6, 2022 at 5:13
  • $\begingroup$ On the opposite side of Puget Sound. And the majority of it on the windward side, which flows west. Some would classify the peaks of the Cascades as seasonal rainforests, but the rain isn't nearly the same level or area (see this graphic). $\endgroup$ Commented Feb 6, 2022 at 7:05
  • $\begingroup$ Olympic Park has basically no connection to Seattle's river levels or tides, since Puget Sound is open sea-level water. $\endgroup$ Commented Feb 6, 2022 at 7:14

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