Some fun September facts from the Old Farmer's Almanac:
September 15—Full Harvest Moon
The Harvest Moon is the full Moon nearest the autumnal equinox and is bright enough to allow finishing all of the harvest chores.
September 17—Citizenship Day
Formerly called Constitution Day, Citizenship Day marks the anniversary of the date in 1787 when the final draft of the constitution of the United States was signed by delegates to the Constitutional Convention after months of wrangling.
September 17, 19, 20—Ember Days
Folklore has it that the weather on each of these three days foretells the weather for three successive months; that is, Wednesday, September 17, forecasts the weather for October; Friday, September 19, for November; and Saturday, September 20, for December.
September 22—Autumnal Equinox
Fall begins at 11:44 A.M. (Eastern Time) today. The autumnal equinox is defined as the point at which the Sun appears to cross the celestial equator from north to south. The celestial equator is the circle in the celestial sphere halfway between the celestial poles. It can be thought of as the plane of Earth’s equator projected out onto the sphere. The word equinox means “equal night,” when night and day are of the same duration.
September 22—Harvest Home
In Europe, the conclusion of the harvest each autumn was once marked by festivals of fun, feasting, and thanksgiving known as “Harvest Home.” It was also a time to hold elections, pay workers, and collect rents. These festivals usually took place around the time of the autumnal equinox.