Here's when fall 2025 starts in Seattle
SEATTLE - While the weather is usually a telling sign, many in the Pacific Northwest are anxiously waiting and asking: when does fall officially start in Seattle?
Astronomical vs meteorological fall
The start of fall is signified by the autumnal equinox, which is on Monday, Sep. 22, 2025 in the Northern Hemisphere. Also known as astronomical fall, it starts once the Sun's center passes through Earth's "celestial equator," or an extension of the equator line if it stretched into space.
However, meteorological fall began on Sep. 1, indicated by the Earth's temperatures. "Meteorological" or "climatological" seasons are divided into three-month periods based on the temperatures that would be expected during each season.
Why fall should actually begin on September 1
Fall might not officially begin until Sept. 22 with the autumnal equinox, but meteorologists and climatologists actually consider Sept. 1 the beginning of autumn.
Timeline:
The start of astronomical fall is between Sep. 22-24 to Dec. 21-23, and meteorological fall is between Sep. 1 and Nov. 30.
What's next:
If you've noticed a shift in Seattle weather recently, you could technically say it's a sign that fall has begun. But a major shift in temperatures Tuesday may make it feel like summer isn't over quite yet.
Seattle weather: Turning warm and hazy on Tuesday
After a cool and sunny Monday, temperatures will soar back into the 80s on Tuesday with hazy sunshine.
After this week though, a long stretch of cooler weather is on its way, coincidentally lining up with the autumnal equinox.
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The Source: Information in this story came from FOX Weather, the Old Farmer's Almanac, the National Weather Service and FOX 13 Seattle reporting.