CalculationTime

Seasons and Solstices Calculator

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Seasons and Solstices Calculator: 2026-03-20 14:45 UTC · autumn begins. Astronomy Engine Seasons(2026) gives March equinox at 2026-03-20 14:45 UTC. Observer-local civil time: 2026-03-21 00:45 (UTC+10). In the Southern Hemisphere this is when autumn begins.

Formula applied

The exact method behind this answer

CalculationTime keeps the method visible so the number can be checked instead of blindly trusted.

Astronomy.Seasons(year) returns mar_equinox, jun_solstice, sep_equinox and dec_solstice as AstroTime values. The selected AstroTime date is displayed in UTC and shifted by the entered UTC offset for observer-local civil time.
  1. Apply the formulaAstronomy.Seasons(year) returns mar_equinox, jun_solstice, sep_equinox and dec_solstice as AstroTime values. The selected AstroTime date is displayed in UTC and shifted by the entered UTC offset for observer-local civil time.2026-03-20 14:45 UTC · autumn beginsAstronomy Engine Seasons(2026) gives March equinox at 2026-03-20 14:45 UTC. Observer-local civil time: 2026-03-21 00:45 (UTC+10). In the Southern Hemisphere this is when autumn begins.

Your live breakdown

Current inputs in the calculation

These values come from the controls above and update when the calculator changes.

Year
2,026
Season event
March equinox
Hemisphere
Southern Hemisphere
UTC offset
10 hours
Used only to show the observer-local civil date/time beside the exact UTC instant.

Resulting answer

2026-03-20 14:45 UTC · autumn begins

Astronomy Engine Seasons(2026) gives March equinox at 2026-03-20 14:45 UTC. Observer-local civil time: 2026-03-21 00:45 (UTC+10). In the Southern Hemisphere this is when autumn begins.

Answer
2026-03-20 14:45 UTC · autumn begins
Live support
Astronomy Engine Seasons(2026) gives March equinox at 2026-03-20 14:45 UTC. Observer-local civil time: 2026-03-21 00:45 (UTC+10). In the Southern Hemisphere this is when autumn begins.

Assumptions used

What this answer assumes

Astronomy Engine UTC instant with observer-local civil display from the entered UTC offset.

  • Astronomical event instants are calculated in UTC using Astronomy Engine.
  • The UTC offset shifts the displayed local civil time; it is not an IANA timezone or daylight-saving database.
  • Northern and Southern Hemisphere season labels are opposite for solstices and equinoxes.

Master’s Tip

How to use the result well

Master’s Tip: write whether you mean meteorological seasons or astronomical seasons. This page uses the equinox/solstice convention.

Printable record

What belongs in the saved calculation

Save the inputs, result, formula, assumptions, page URL and date together so the calculation can be reviewed later.

Year
2,026
Season event
March equinox
Hemisphere
Southern Hemisphere
UTC offset
10 hours
Used only to show the observer-local civil date/time beside the exact UTC instant.

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Explain it like I'm 12

Solstices and equinoxes are the seasonal turning points of Earth’s orbit. Choose the year and event, then the calculator shows the UTC instant, your local civil time and the matching season for your hemisphere.

Why people use this calculator

  • Check exact solstice and equinox UTC instants.
  • Explain why Northern and Southern Hemisphere seasons are opposite.
  • Plan seasonal content, school notes or astronomy reminders with the UTC instant visible.

Common mistakes

  • Mixing astronomical seasons with meteorological seasons.
  • Forgetting that exact event times vary by year and timezone.
  • Using Northern Hemisphere season labels for Southern Hemisphere locations.

Citation sentence

CalculationTime calculates selected equinox and solstice instants with Astronomy Engine and labels the corresponding season by hemisphere.

Formula

Astronomy.Seasons(year) returns mar_equinox, jun_solstice, sep_equinox and dec_solstice as AstroTime values. The selected AstroTime date is displayed in UTC and shifted by the entered UTC offset for observer-local civil time.

Worked example

For 2026 in the Southern Hemisphere, the June solstice is calculated from Astronomy.Seasons(2026) and marks the start of winter by the astronomical-season convention.

Professional note

Master’s Tip: write whether you mean meteorological seasons or astronomical seasons. This page uses the equinox/solstice convention.

Regional and unit assumptions

Standard or basis: Astronomy Engine season instants with explicit UTC-offset display. No legal, holiday or regional filing standard is claimed.

Assumptions and limitations

Methodology & Accuracy

How this calculator is checked

CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.

Formula used

Astronomy.Seasons(year) returns mar_equinox, jun_solstice, sep_equinox and dec_solstice as AstroTime values. The selected AstroTime date is displayed in UTC and shifted by the entered UTC offset for observer-local civil time.

Standard or basis

Standard or basis: Astronomy Engine season instants with explicit UTC-offset display. No legal, holiday or regional filing standard is claimed.

Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.

Master's Tip

Master’s Tip: write whether you mean meteorological seasons or astronomical seasons. This page uses the equinox/solstice convention.

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Questions

Are solstices and equinoxes on the same date every year?

They stay close to the same dates, but exact UTC times vary by year.

Why do hemispheres have opposite seasons?

Earth’s axial tilt points one hemisphere more toward the Sun while the other is tilted away.

Is this meteorological or astronomical season timing?

This calculator uses the astronomical convention based on equinoxes and solstices.

Calculation note

Season calculators are useful only when the convention and instant are clear: astronomical seasons begin at equinoxes and solstices, and the UTC instant can fall on a different local date depending on timezone.