Seasons Start And End | When Do The Four

| Season | Astronomical Start | Astronomical End | Meteorological | |------------|--------------------------|--------------------------|----------------| | Spring | Mar 20–21 (Equinox) | Jun 20–21 (Solstice) | Mar 1 – May 31 | | Summer | Jun 20–21 (Solstice) | Sep 22–23 (Equinox) | Jun 1 – Aug 31 | | Autumn | Sep 22–23 (Equinox) | Dec 21–22 (Solstice) | Sep 1 – Nov 30 | | Winter | Dec 21–22 (Solstice) | Mar 20–21 (Equinox) | Dec 1 – Feb 28/29 |

Why: September, October, and November represent the transition from summer heat to winter cold. September 1 is the logical start of the cooling trend.

The dates above apply to the Northern Hemisphere (North America, Europe, most of Asia). If you are in the Southern Hemisphere (Australia, South America, parts of Africa), the seasons are reversed:

Meteorologists (weather scientists) divide the year into four neat seasons made up of three full months each. This makes calculating weather statistics and averages much easier.

Best for: Gardening, tracking weather patterns, and simplicity. when do the four seasons start and end

For a quick reference, here is how the two systems contrast for the Northern Hemisphere:

| Season | Meteorological Start | Meteorological End | Astronomical Start (approx) | Astronomical End (approx) | | :--- | :--- | :--- | :--- | :--- | | Spring | March 1 | May 31 | March 20 | June 21 | | Summer | June 1 | August 31 | June 21 | September 22 | | Autumn | September 1 | November 30 | September 22 | December 21 | | Winter | December 1 | February 28/29 | December 21 | March 20 |

(Note: Dates for the Southern Hemisphere are reversed. When it is astronomical summer in the north (June 21), it is astronomical winter in the south.)

Why: December, January, and February are statistically the coldest three-month period. This is why "winter storms" in early December feel appropriate, while the astronomical winter hasn't technically begun yet. | Season | Astronomical Start | Astronomical End

Key advantage: Meteorological seasons are fixed. They always start on the same day of the same month. This makes calculating seasonal statistics (average temperature, total rainfall, heating degree days) incredibly easy.

Definition

  • These dates shift slightly each year because Earth’s orbit isn’t an exact number of days and because of leap years.

    • Why they matter

    Typical dates (Northern Hemisphere)

    Each astronomical season runs from one event to the next:

    Southern Hemisphere: swap spring/summer/fall/winter. For instance, the December solstice is the start of summer there.

    Irregularities and precise timing

    Implications

    🔥 Solstice = longest/shortest day of the year.

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