The autumnal equinox heralds the arrival of fall in the northern hemisphere, and it's just around the corner. Here's what to know.

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.

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,