When is the first day of Fall 2026? What the Equinox means in the Pacific Northwest

Fall officially arrives in the Pacific Northwest this week, bringing the region into a season of shorter days, cooler weather, changing leaves, and eventually much earlier sunsets.

The autumnal equinox, which marks the astronomical beginning of fall in the Northern Hemisphere, occurs Tuesday, Sept. 22, 2026.

For Oregon and Washington, the equinox happens at 5:05 p.m. Pacific time, according to NASA.

Here’s what to know about the first day of fall and what changes after the equinox.

When does fall officially begin in 2026?

Astronomical fall begins at 5:05 p.m. PDT on Tuesday, Sept. 22, when the September equinox occurs.

An equinox happens twice each year, once in March and again in September. It marks the moment when the center of the sun crosses the plane of Earth’s equator.

The September equinox signals the beginning of astronomical fall in the Northern Hemisphere and astronomical spring in the Southern Hemisphere.

Why are day and night nearly equal during the equinox?

The word “equinox” comes from Latin words referring to equal and night, but that does not mean every location receives exactly 12 hours of daylight and 12 hours of darkness.

Day and night are close to equal around the equinox, with the exact amount of daylight depending on location and how sunrise and sunset are measured.

In Portland, for example, the sun is expected to rise around 6:58 a.m. and set around 7:07 p.m. on Sept. 22, providing about 12 hours and 10 minutes of daylight.

Has fall already started for meteorologists?

Yes. Meteorological fall began Sept. 1.

Meteorologists divide the year into four three-month seasons, making it easier to track and compare weather and climate data. Meteorological fall includes September, October, and November.

Astronomical seasons are based instead on Earth’s position in its orbit around the sun, with equinoxes and solstices marking the seasonal changes.

What happens to daylight after the fall equinox?

Pacific Northwest days will continue getting shorter after the equinox.

In Portland, daylight is decreasing by a little more than three minutes per day around the start of fall. The trend continues until the winter solstice on Dec. 21, which brings the shortest day of the year in the Northern Hemisphere.

For locals and travelers, the shrinking daylight becomes increasingly noticeable through October and November, especially for hiking, scenic drives, and other outdoor plans.

When does Daylight Saving Time end in 2026?

Another major change arrives Sunday, Nov. 1, when daylight saving time ends in Oregon and Washington. Clocks “fall back” one hour at 2 a.m., shifting an hour of daylight from the evening to the morning.

When does winter begin in 2026?

Astronomical fall lasts until the winter solstice on Monday, Dec. 21.

Until then, Pacific Northwest residents can expect progressively shorter days as the region moves deeper into fall and toward the darkest weeks of the year.