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CalcSpan/Countdowns, holidays and school calendars/Season Solstice Equinox Countdown
Countdowns, holidays and school calendars · Guide + calculator Without the guesswork.

Season, Solstice & Equinox Countdown

Count down to the next equinox or solstice with hemisphere-correct season names and a transparent local-time offset. Inputs stay in your browser.

Reference toolSeason Solstice Equinox CountdownCount down to the next equinox or solstice with hemisphere-correct season names and a transparent local-time offset. Inputs stay in your browser.
Reference calculation

Enter your details.

Calculated locally in your browser. Nothing is uploaded to CalcSpan.

Mon, Aug 24, 2026
Use the offset in effect on this date.

Plain-date semantics · start date is not counted unless the result explicitly says inclusive.

Your result
29 days 12 hours 5 minutes until fall equinox

Fall equinox begins at Sep 23, 2026 at 00:05 (UTC) for the selected display offset.

Next seasonal eventFall equinoxSep 23, 2026 at 00:05 (UTC)
Countdown29 days 12 hours 5 minutes
HemisphereNorthern Hemisphere
AlgorithmMeeus equinox/solstice polynomial · 4.0.0Tested against USNO 2026 event times
Timeline
Sep 23, 2026Fall equinox · 00:05 (UTC)
Dec 21, 2026Winter solstice · 20:50 (UTC)
Mar 20, 2027Spring equinox · 20:25 (UTC)
Jun 21, 2027Summer solstice · 14:11 (UTC)
Calendar options

Add to calendar

Choose a calendar service, then confirm the event. Downloading an .ics file does not add it until you open or import it.

Read before relying

Context matters.

  • Equinox and solstice instants are global; season names reverse between hemispheres.
  • This is one evergreen calculator. CalcSpan does not generate thin year-only copies.
Rule set 1.1.0

Sources & scope

Source & calculation QA reviewed

The calculation guide and this source trail show what the result means, where the rule came from and when it was last reviewed. This is source-and-calculation QA, not a claim of medical, legal, tax or other professional review; time-sensitive decisions still belong with the linked authority.

U.S. Naval Observatory · SRC-USNO-SEASONS-001Earth's Seasons — Equinoxes and SolsticesSource retrieved 2026-08-23
JurisdictionGlobal equinox and solstice instants — hemisphere controls season names and entered UTC offset controls display time
Last reviewed2026-08-23
Next review due2027-02-23
Review scopeCalcSpan source & calculation QA
PrivacyNo input upload
How this calculation works

A visible path from input to answer.

Count down to the next equinox or solstice with hemisphere-correct season names and a transparent local-time offset. The page keeps the calculation scope and its limits beside the result so the output can be checked, copied or revisited.

Calculation flow
  1. Read the record. The calculator uses Date, Local time, UTC offset (hours) and Hemisphere supplied in the form.
  2. Apply the scope. It applies the Global equinox and solstice instants — hemisphere controls season names and entered UTC offset controls display time reference and the explicit date, unit and counting conventions shown in the result.
  3. Expose the checkpoints. Intermediate rows, warnings and timeline events stay visible; the emphasized row identifies the primary checkpoint when one exists.
Illustrative default example 29 days 12 hours 5 minutes until fall equinox

Fall equinox begins at Sep 23, 2026 at 00:05 (UTC) for the selected display offset.

  • Next seasonal eventFall equinox
Defaults are an illustration only. Replace them with the record that applies to your situation.
Assumptions and scope

Calculation purpose: Count down to the next equinox or solstice with hemisphere-correct season names and a transparent local-time offset. This is a high-sensitivity reference output; the linked authority or qualified professional controls the final decision.

Boundary behavior

Calendar inputs use plain year-month-day semantics. Leap days, month ends, date-pair order and unsupported dates are checked before the result is shown.

Rule trail

Rule set 1.1.0 · Last reviewed 2026-08-23 · Next review due 2027-02-23. The source panel below contains the linked evidence.

Questions answered

What to know before using the result.

When does spring start?

The calculator uses the March equinox for Northern Hemisphere spring and September equinox for Southern Hemisphere spring.

Are equinox and solstice times local?

The astronomical instant is global. CalcSpan converts that instant to the UTC offset entered for display.

Why is this an evergreen page?

The calculation updates from the entered date and does not need duplicate year-only pages.

Keep going

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