Autumnal Equinox Arrives Tuesday, Marking Start of Fall in San Diego

San Diego, CA, September 22, 2026 —

The autumnal equinox is set to occur on Tuesday, officially marking the beginning of the fall season in San Diego. This celestial event signifies a shift in the Earth’s position relative to the sun, bringing changes in daylight hours and atmospheric conditions to the region.

The equinox is a moment in time, occurring only once a year, when the tilt of the Earth’s axis is at a 90-degree angle to the orbital plane. On this day, the sun appears directly over the Earth’s equator. For locations in the Northern Hemisphere, including San Diego, this means that day and night will be of approximately equal length. Following the autumnal equinox, the Northern Hemisphere will begin to tilt away from the sun, leading to shorter days and longer nights as winter approaches.

The precise timing of the autumnal equinox can vary slightly from year to year due to the Earth’s elliptical orbit and the Gregorian calendar’s adjustments for leap years. While the exact time for this year’s equinox was not specified in the provided summary, its occurrence on Tuesday will be the key indicator of the seasonal transition.

Residents of San Diego can anticipate a gradual change in weather patterns associated with the onset of autumn. Typically, this season brings cooler temperatures, less humidity, and a decrease in the length of daylight hours. The autumnal equinox serves as a natural calendar marker, recognized by cultures worldwide as a time of transition and change. The significance of the equinox extends beyond its astronomical definition, often being associated with harvests and shifts in natural cycles.

Story summarized from the original created by Google News on news.google.com, see more information here.