The ‘Season of mists and mellow fruitfulness’, so Keats described Autumn. A time to give thanks and celebrate the gathering of the year’s harvest. A time of cooling temperatures, shortening days and darkening nights. But when exactly does Autumn start?

Meteorological and Astronomical Seasons:
For Meteorologists to be able to accurately record climate data, it is important to have set dates. Therefore the year is split into 4 seasons containing 3 equal months:

Spring: March, April, May – starting on March 1st
Summer: June, July, August – starting on June 1st
Autumn: September, October, November – starting on September 1st
Winter: December, January, February – starting on December 1st

The Astronomical seasons use the position of the Earth’s orbit in relation to the Sun to determine the equinoxes and solstices. Due to the tilt of the Earth, the seasons vary in length; therefore the start date of a new season can fall on different days each year. The Autumn Equinox occurs every September; however the actual date can vary from the 22nd to the 24th. In 2020 it falls on Tuesday the 22nd of September.

An equinox occurs when the position of the sun is exactly over the equator, resulting in the same length of daylight hours and darkness – 12 hours all over the world. This is the reason it’s called an “equinox,” derived from Latin, meaning “equal night.” In reality, equinoxes don’t have exactly 12 hours of daylight.