Start And End — When Do The Four Seasons

The ancient Celts defined seasons based on the solar cross-quarter days (the midpoints between solstices and equinoxes):

Starts at the March Equinox ( March 19–21 ) and ends at the June Solstice ( June 20–22 ). Meteorological: Starts on March 1 and ends on May 31 .

June, July, and August are the three warmest months of the year for most locations. June 1 is a clean, non-varying date that allows weather agencies to compare seasonal data year-over-year without leap year adjustments.

For a quick reference, here is how the two systems contrast for the Northern Hemisphere: when do the four seasons start and end

Scientists, meteorologists, and calendar makers divide the year using two main frameworks. Both are accurate, but they serve completely different purposes. 1. Astronomical Seasons (Based on the Earth and Sun)

However, scientists have observed a phenomenon called Over the past 50 years:

The timing of the seasons depends on whether you follow the calendar (based on Earth's position relative to the sun) or the meteorological calendar (based on temperature cycles). 📅 Astronomical Seasons (2026) The ancient Celts defined seasons based on the

As if two systems weren't enough, many cultures and industries define seasons by local ecology or tradition. These are less precise but often more meaningful.

Summer brings the warmest temperatures of the year and the longest hours of daylight.

Starts on September 1 and ends on November 30 . June 1 is a clean, non-varying date that

Phenological seasons

2. Meteorological Seasons (Based on the Calendar and Temperature)