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Season Dates Calculator

Work out season dates instantly with clear inputs, formula shown and shareable results.

About Season Dates Calculator

Astronomical seasons begin at the equinoxes and solstices, which fall around 20 March, 21 June, 22 September and 21 December. The hemispheres are offset by six months, so the March equinox opens spring in the north and autumn in the south. Meteorological seasons instead start on the first of March, June, September and December.

Formulas

Astronomical seasons

begin at the equinoxes and solstices

Hemisphere offset

southern seasons are shifted by six months

Worked example

With the default values below, Season Dates Calculator returns Spring Begins of 2026-03-20. Change any input above and every figure here is recalculated in your browser.

Inputs used

Yearaccepts 1,900–2,200
2,026
Hemisphereone of Northern, Southern
Northern

Results

Spring Begins
2026-03-20
Summer Begins
2026-06-21
Autumn Begins
2026-09-22
Winter Begins
2026-12-21

Step by step

  1. 1Values used
  2. 2Astronomical seasons
  3. 3Hemisphere offset
  4. 4Spring Begins= 2026-03-20
  5. 5Summer Begins= 2026-06-21
  6. 6Autumn Begins= 2026-09-22
  7. 7Winter Begins= 2026-12-21

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why do the dates shift between years?

Because the tropical year is 365.2422 days, so each event drifts about six hours later annually until a leap day resets it.

Which definition should I use?

Meteorological seasons for climate statistics, since they align with calendar months. Astronomical seasons for daylight and solar geometry.

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