When does fall start? Seattle peak fall colors, leaves dates

Name: Here's what September weather looks like in Seattle
Uploaded: 2026-09-01T10:55:06-07:00
Duration: 1 min 44 s
Description: Meteorological fall has officially begun. Chief Meteorologist Brian MacMillan recaps summer 2026 weather totals and and outlook for the typical September in Seattle.

Here's what September weather looks like in Seattle

Meteorological fall has officially begun. Chief Meteorologist Brian MacMillan recaps summer 2026 weather totals and and outlook for the typical September in Seattle.

SEATTLE - As summer winds down, the transition into a new season brings shifts in the weather, the calendar, the clock, and soon, the trees.

From tracking the exact first day of fall to finding out when autumn foliage will peak across Washington, here is everything you need to know about the seasonal shift.

Japanese Garden in autumn, Washington Park Arboretum, Seattle, Washington. (Photo by: Greg Vaughn /VW PICS/Universal Images Group via Getty Images)

When does summer end?

Summer has an official expiration date depending on whether you are looking at the calendar or the weather outside. While meteorological summer wrapped up at the end of August, astronomical summer continues right up until the autumn equinox later in September.

When does meteorological fall begin?

According to FOX 13 Seattle Chief Meteorologist Brian MacMillan, meteorologists recognize a distinct start to the season based on annual temperature cycles on the calendar.

"We have meteorological fall, which is recognized by the National Oceanic Atmospheric Administration (NOAA), and this is based on the weather," MacMillan explains. This season spans the three transition months between summer and winter in the Northern Hemisphere, starting on September 1 and running through the end of November before meteorological winter kicks off on December 1. Grouping the seasons into months helps with record keeping because the astronomical seasons can vary in length.

When's the first day of fall?

For most people, the official change of seasons is marked by the Earth's tilt and orbit. MacMillan notes that astronomical fall – "Which most of us think as fall" – is traditional and based on the sun's position. This is driven by the fall equinox, bringing roughly equal lengths of daytime and nighttime. This year, the astronomical autumn equinox occurs on September 22, meaning we are just a few weeks away from the seasonal shift.

When will the fall leaves reach peak color in Seattle and across WA?

Typically, western Washington and the Seattle area see peak fall foliage arriving by mid-to-late October, depending on microclimates and elevation. Fall colors tend to peak earlier at higher elevations.

The Northern Washington Cascades typically peak in late September, with most of the Cascades and Olympic Mountains following in early October.
The Puget Sound lowlands generally reach peak colors between mid to late October.

There are many variables involved when it comes to leaves reaching peak color. Similar to past dry and warm summer patterns, moisture stress and temperature shifts can impact the timing, sometimes causing leaves to reach peak color earlier than usual.

Seattle summer weather recap

Looking back at our weather records, June and August both had warmer-than-normal temperatures, while July was just slightly cooler than average. Overall, Seattle's 2026 summer was about 1° above average. The hottest day was July 22, 2026, when we hit 95°, and we hit 90° or warmer four times over the summer.

As far as precipitation goes, it was dry all summer long. June, July, and August were all drier than normal—and we had a 33-day dry streak between July 27 and August 28. The good news: we did not have as much wildfire smoke in the Puget Sound area this past summer.

What does September weather look like in Seattle?

According to MacMillan, September in Seattle is typically cooler, it turns darker, and it's wetter—with average rainfall at around 1.61 inches, whereas in August we averaged under an inch of rain. The average last 80° day is September 13, but according to MacMillan, "there is still plenty of nice weather in an average September to go ahead—in fact, we have pretty good weather until mid-October before things really turn."

When is Labor Day?

Marking the unofficial close of the summer season, Labor Day falls on Monday, September 7, 2026.

When is daylight saving this year?

As the seasons continue to shift later into the year, daylight saving time will come to an end on Sunday, November 1, 2026, requiring clocks to fall back one hour.

The Source: Information in this story comes from original reporting by FOX 13 Seattle Chief Meteorologist Brian MacMillan and previous reporting from the FOX 13 Seattle Digital Team, including the 2025 article, "Here’s when fall leaves will hit peak color in Seattle and across Washington."