Farmers rely on the Spring Equinox to determine planting times and the Fall Equinox to begin the harvest.
To understand why the astronomical dates exist, you need to know the four key celestial events:
This definition is based on the position of the Earth in relation to the Sun. The dates are determined by the and equinoxes .
These seasons are defined by the two solstices and two equinoxes. These dates can vary slightly from year to year (usually by a day or two) due to the Earth's elliptical orbit and the leap year cycle. dates of seasons
If you want to mark the official change in daylight and Earth's orbit, follow the astronomical dates (solstices and equinoxes). If you want a simpler, consistent way to track the weather, follow the meteorological seasons.
Points where the Sun reaches its highest or lowest point in the sky at noon, resulting in the longest and shortest days of the year. Meteorological Seasons
The astronomical definition is the traditional "official" method used by most calendars. It relies on specific points in Earth's orbit where the tilt of its axis most affects daylight. Farmers rely on the Spring Equinox to determine
Because our calendar year is exactly 365 days, we "lose" about six hours every year. We correct this with a every four years, which resets the astronomical clock and keeps our seasons from drifting into different months over centuries. The Significance of Season Dates
While the scientific dates are standard today, many cultures historically defined seasons differently.
Before looking at the calendar, it is important to understand why you often see different dates on weather apps versus astronomy charts. These seasons are defined by the two solstices
For millennia, the dates of seasons have dictated human behavior.
| Season | Astronomical Start | Meteorological Start | | :--- | :--- | :--- | | | March 20, 2025 | March 1 | | Summer | June 20, 2025 | June 1 | | Autumn | September 22, 2025 | September 1 | | Winter | December 21, 2025 | December 1 |