Season Countdown

When do astronomical seasons begin?

Astronomical seasons are defined by solstices and equinoxes. Spring starts at the March equinox (around March 20-21), summer at the June solstice (around June 20-21), autumn at the September equinox and winter at the December solstice.

Solstices vs Equinoxes

At a solstice, the Sun reaches its maximum or minimum declination — the longest day (summer solstice) or shortest day (winter solstice). At an equinox, day and night are nearly equal in length (approximately 12h each).

Northern vs Southern Hemisphere

When it is summer in the Northern Hemisphere (Canada, Europe, US), it is winter in the Southern Hemisphere (Australia, Argentina, South Africa). Seasons are reversed but occur on the same astronomical dates.