We can all agree that September, October and November are the fall months. However, there seems to be some controversy about the date the season begins.
Sept. 22 is called the "First Day of Autumn" in our calendars this year. However, these calendrical dates are intended to mark the seasons with reference to the positions of the sun in the sky. Some meteorologists, in objection to the equinoctial first day of fall, have insisted that Sept. 1 is the true start of "meteorological fall." However, the first day of September is no more important to the change of the season than the 22nd, or any other day, for that matter.
Seasons change around the same time every year, but there is no particular date upon which they turn. This meteorologist would argue that Sept. 1 through Nov. 30 should be called "climatological fall" as the only useful purpose of using dates to demark the seasons from one another is for comparative purposes of climatology.