Fall is here! What to know about autumn equinox

Autumn officially started Thursday at 7:21 a.m. PDT

Autumn leaves, file. (vivek jena via Flickr Creative Commons)
Autumn leaves, file. (vivek jena via Flickr Creative Commons)

PORTLAND, Ore. (KOIN) — Get your coats ready, fall is officially here!

It is that time of year when the leaves start to change color, the skies turn gray and the temperatures start to drop.

Colorful leaves in Portland, file. (Ian Sane via Flickr Creative Commons)
Colorful leaves in Portland, file. (Ian Sane via Flickr Creative Commons)

The Pacific Northwest transitioned to autumn Thursday at 7:21 a.m. PDT, the exact moment the sun crossed the celestial equator.

Fall typically arrives on September 22 or 23, but the exact day can vary. That’s because the Earth’s yearly trip around the sun ends up being a little more than 365 days — roughly 365 1/4 — which is also why we have a leap year every 4 years.

The transitions to spring and autumn are referred to as equinoxes because they bring nearly equal hours of daylight and nighttime. They’re different than the start of summer, the longest day of the year, and the start of winter, the longest night.

Days will continue to get shorter until the winter solstice, the first day of winter, on December 21. There will only be 8 hours and 42 minutes of sunlight that day.

As we transition to fall in the northern hemisphere, people south of the equator are gearing up for their summer. That’s because the Earth orbits the sun on a tilted axis. When one hemisphere is pointed towards the sun, the other is pointed away from it. Whichever hemisphere is tilted towards the sun experiences summer.

Temperatures in Portland will keep dropping throughout autumn. Daily highs start in the mid-70s and drop to the mid-40s by the end of the season on December 20.

Even though fall just started Thursday, meteorological fall started on September 1 and goes through the end of November. Download the PDX Weather App and follow the KOIN 6 Weather Team to find out just how cool and wet this season will be.

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