Days Until Next Season Calculator
Count down to the first day of summer, spring, autumn or winter from any date — with the exact equinox or solstice date and time in your time zone, northern or southern hemisphere, astronomical or meteorological seasons.
How it works
days = start date of the season (on or after your date) − your date · astronomical starts = the March and September equinoxes and the June and December solstices, computed for each year (Meeus) and converted to your time zone · meteorological starts = March 1, June 1, September 1, December 1 · southern hemisphere: shifted by six months
Astronomical seasons begin at an exact instant: the moment of the March or September equinox, when the Sun crosses the celestial equator, or the June or December solstice, when it is farthest north or south. Those moments drift by several hours from year to year and fall between March 19–21, June 20–21, September 22–23 and December 21–22, so the calculator works them out for each year with Jean Meeus’s astronomical formulas and converts them to the time zone you choose — the same equinox can be September 22 in the Americas and September 23 in Europe. It then counts the days from your date to the next start of the season you picked, and also tells you which season you are in and how far along it is. Meteorological seasons, used by weather services, simply start on the 1st of March, June, September and December. In the southern hemisphere everything shifts by six months: the December solstice starts summer.
Worked example
Counting from October 18, 2026 to summer in the northern hemisphere: the June solstice of 2027 is at 14:11 UTC on June 21, which is 10:11 in New York (EDT, UTC−4) — Monday, June 21, 2027, 246 days or 35 weeks and 1 day away. Choosing “the next season (any)” lands on winter, which starts with the December solstice on Monday, December 21, 2026 at 15:50 New York time, 64 days away. Today, October 18, is day 26 of autumn, which began on September 22 in the Americas (September 23 in Europe). With meteorological seasons, winter starts on December 1 instead — 44 days away.
Sources: US Naval Observatory — Earth’s seasons and apsides · Meeus, J. — Astronomical Algorithms, 2nd ed., chapter 27 (Willmann-Bell, 1998)
Frequently asked questions
Why does the first day of a season change from year to year?
A year is about 365.24 days, so each equinox or solstice comes roughly six hours later than the year before, and jumps back after a leap day. That is why the start of spring falls on March 19, 20 or 21. This calculator computes the exact moment for each year instead of using a fixed date.
Why can the date depend on my time zone?
An equinox or solstice happens at one instant for the whole planet. When that instant is close to midnight UTC — as with the September 2026 equinox at 00:05 UTC — it is still September 22 in the Americas but already September 23 in Europe. Choose your time zone under More options.
What is the difference between astronomical and meteorological seasons?
Astronomical seasons start at the solstices and equinoxes. Meteorological seasons are whole months — March to May is spring in the north, June to August summer, and so on — which makes weather statistics easier to compare. They start about three weeks earlier.
How do southern-hemisphere seasons differ?
They are offset by six months: the December solstice begins summer and the June solstice begins winter. Select the southern hemisphere and the dates swap automatically.
Are the seasons the same length?
No. Earth moves faster when it is closer to the Sun in early January, so northern winter is the shortest astronomical season (about 89 days) and northern summer the longest (about 93–94 days). The chart shows the length of each upcoming season.
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This calculator is for educational purposes. Double-check important results before acting on them.