It's September! While the equinox isn't until later this month, meteorological autumn begins today. There are two separate dates which can be used to define the start of the season.

Astronomically, the start of autumn takes place on the equinox, when the length of day and night are the same in all parts of the world. It is defined by the Earth's axis and orbit around the Sun, and the exact date varies each year slightly.

This year, the autumn equinox falls on September 22nd at 08:05 pm ET, with the astronomical autumn running until December 21st.

Meteorologically, seasons are fixed dates because it is statistically easier to process the data by taking four equal quarters for each of the four seasons.

Meteorological autumn in the Northern Hemisphere begins on September 1st and runs through October and November, with meteorological winter beginning on December 1st.

While the days are really getting shorter and cooler for us, the opposite is true for those in the Southern Hemisphere.