Seasons Calculator
In the Northern Hemisphere in 2026, fall starts on September 23 and winter starts on December 21. This seasons calculator shows the first day of spring, summer, fall, and winter for any year. Switch between the astronomical calendar, which uses the equinoxes and solstices, and the meteorological calendar, which uses fixed month starts, and pick your hemisphere.
Quick answer
Astronomical seasons begin at the equinoxes and solstices, which shift by a day or so each year.
What this tells you
- •Astronomical seasons begin at the equinoxes and solstices, which shift by a day or so each year.
- •Meteorological seasons begin on fixed dates: the first of March, June, September, and December.
- •The Southern Hemisphere has opposite seasons, so its spring starts when the north begins fall.
- •Astronomical dates are shown in UTC and can fall a day earlier or later in your local time.
How to Use
- 1Enter the year you want to check. It defaults to the current year.
- 2Pick your hemisphere, since seasons are flipped north and south.
- 3Choose the astronomical or meteorological calendar.
- 4Read the start date for each of the four seasons.
How It Works
Formula
astronomical season start = equinox or solstice instant; meteorological = fixed first of the monthAstronomical seasons start at the moment of an equinox or solstice, found from the Sun's position using a standard astronomical method, so the date moves slightly each year. Meteorological seasons group whole months and always start on the first of March, June, September, and December. Season names are then matched to your hemisphere.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
When does fall start in 2026?
In 2026 the September equinox lands on the 23rd in UTC, which marks the astronomical start of fall in the Northern Hemisphere.
When does winter start in 2026?
The December solstice in 2026 falls on the 21st, the shortest day of the year and the astronomical start of winter in the north.
Northern Hemisphere Season Starts (Astronomical)
First day of each season by the equinoxes and solstices, in UTC.
| Year | Spring | Summer | Fall | Winter |
|---|---|---|---|---|
| 2024 | Mar 20 | Jun 20 | Sep 22 | Dec 21 |
| 2025 | Mar 20 | Jun 21 | Sep 22 | Dec 21 |
| 2026 | Mar 20 | Jun 21 | Sep 23 | Dec 21 |
| 2027 | Mar 20 | Jun 21 | Sep 23 | Dec 22 |
Dates are UTC and may differ by a day in your local time zone. Southern Hemisphere seasons are the opposite, so its fall starts on the March date.
Common mistakes
- Assuming seasons always start on the same date. Astronomical season dates shift by a day or two each year because the equinoxes and solstices do.
- Mixing up the two calendars. Meteorological fall starts September 1, while astronomical fall starts at the September equinox around the 22nd or 23rd.
- Forgetting the hemisphere. When it is fall in the north it is spring in the south, so the same date marks opposite seasons.