The official first day of fall, otherwise known as the autumnal equinox, is this weekend in the Northern Hemisphere. According to Encyclopedia Britannica, it is one of only two days, the other being the vernal equinox, when the sun is directly above the Equator, essentially dividing night and day into equal portions.

The first day of fall, also known as the autumnal equinox, is Sunday, Sept. 22, at 8:44 a.m. ET. While the equinox is known as the astronomical start of the season, there is another method used to measure the change in seasons. The meteorological beginnings of seasons are based on the annual temperature cycle and the 12-month calendar.

Fall weather is soon going to be hitting the Northeast and just in time as the official start to fall — the autumnal equinox — is about to arrive. The fall — or autumnal — equinox can land on Sept. 22 or 23 depending on the year This year,

The autumnal equinox marks the changing of the seasons, shortening the hours of daylight in the Northern Hemisphere.

The seasons are changing and so is the amount of daylight we get here in the Pikes Peak region. The first official day of fall is Sunday, Sept. 22–sometimes described as the fall/autumn equinox. The word ‘equinox’ actually means equal night in Latin.