We are well into meteorological fall, however the calendar is still showing summer. So, which is it? The short answer is both.

Meteorological seasons are made up by scientists.
Astronomical seasons are based on the calendar.

Every year on September 1st, meteorological fall begins. The months of September, October and November are all a part of meteorological fall. Meteorological season dates do not change. The beginning and end dates of the autumn equinox do change every year. The 2023 autumnal equinox begins on September 23 at 1:30am CST and will end on December 21, 2023.

The meteorological start of a season is based on the 12-month calendar and the annual temperature cycle. Each season begins on the first of a particular month and lasts for three months. Spring begins on March 1, summer on June 1, autumn on September 1 and winter on December 1. This way of record keeping was created by climate scientists and meteorologists, making it easier since the season doesn’t change from year to year.

The astronomical start of a season is based on the position of the Earth in relation to the Sun. The start of each season is marked by a solstice (for winter and summer) or an equinox (for spring and autumn). A solstice occurs when the Sun reaches the most southerly (winter) or northerly(summer) point in the sky. During an equinox the sun passes over Earth’s equator. The dates of the equinoxes and solstices can shift by a day or two over time thanks to leap years, causing the start dates of the seasons to shift.

Meteorological seasons:

Spring – March, April, May
Summer – June, July, August
Fall – September, October, November
Winter – December, January, February