TOPEKA (KSNT) – We are just days away from the official start of fall, a farewell to summer in the Northern Hemisphere.

Typically, autumn arrives on Sep. 21, but this year it arrives on Saturday, Sept. 23 at 1:50 a.m. Leap years can cause seasons to shift a day or two over time. The autumnal equinox happens when the sun crosses the equator from north to south, creating roughly equal daylight and darkness on that date, and a few days on either side.

While fall doesn’t officially start until mid to late September on the autumnal equinox, known as “astronomical fall”, there is also something called “meteorological fall” that 27 News Chief Meteorologist Matt Miller often refers to, and that began on Sept. 1. 

Meteorologists divide the year up into four seasons based on the annual temperature cycle, while astronomers determine the seasons by the Earth’s tilt. For example, fall for meteorologists is Sept. 1 through Nov. 30. Winter starts on Dec. 1 and ends on the last day in February. In comparison, fall for astronomers (and the general public) begins with the autumnal equinox and winter begins with the winter solstice.