September is the ninth month of the Gregorian calendar, but the month’s name is derived from septem, Latin for “seven,” which was its position in the early Roman calendar.
September is the month of the Autumnal Equinox which occurs on the 22nd at 9:03 PM. Is it always on September 22nd? In the Northern Hemisphere, the autumnal equinox falls on September 22 or 23. In the Southern Hemisphere, the equinox occurs on March 20 or 21.
In the Northern Hemisphere, the equinox is when the Sun crosses the celestial equator going south. In the Southern Hemisphere, the equinox is when the Sun moves north across the celestial equator.

Today we move into autumn, also known as fall in North American English. Which word do you tend to use? The origin of “autumn” and “fall” for the season is interesting. Did you know that at one time (and still in some places) the season is called “Harvest?”
This transitional period from summer to winter is when (unless you’re in the tropics) daylight becomes noticeably shorter and the temperature cools considerably. This is best known as the time when the leaves of deciduous trees change colors as they prepare to shed. Early predictions for Paradelle here in the northeast is that a lack of rain this summer will mean a less-than-spectacular color foliage show.
Temperatures now seem to switch between summer heat and winter chills, but that is true only in middle and high latitudes. In equatorial regions, temperatures generally vary little during the year, and in polar regions, autumn is very short.