The fall season is here, as marked by the autumnal equinox, which will happen Monday.

The autumnal equinox will occur Monday, Sept. 22, at 12:19 p.m. MT/1:19 p.m. CT, signaling the end of summer. The word "equinox" comes from the Latin words "aequalis" and "nox," meaning "equal night." On the autumnal (and the spring) equinox, day and night are roughly 12 hours long in most of the world.

During the autumnal equinox, the Earth's axis is tilted neither toward nor away from the sun, resulting in a "nearly" equal amount of daylight and darkness at all latitudes, according to the National Weather Service .

Here's what to know about the start of fall.

When does fall officially start?

This year, the autumnal equinox falls at 12:19 p.m. MT/1:19 p.m. CT on Monday, Sept. 22, signaling the

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