For those in the (like North America, Europe, and much of Asia), the 2026 start dates are as follows: Meteorological Start Astronomical Start (2026) Spring Summer Autumn (Fall) September 1 September 22 Winter December 1 December 21 The Southern Hemisphere Flip

Meteorologists and climatologists split the year into neat, three-month blocks based on temperature patterns and the calendar. This makes seasonal climate statistics and forecasting much easier.

Seasons are reversed south of the equator. When the Northern Hemisphere tilts toward the Sun, the Southern Hemisphere tilts away. Meteorological Versus Astronomical Seasons | News

The first day of spring, summer, fall, or winter isn’t as fixed as you might think. In fact, there are two widely accepted calendars: the (based on Earth’s orbit around the sun) and the meteorological (based on annual temperature cycles and the calendar for simpler record-keeping).

To make climate statistics easier to compare, meteorologists divide the year into four 3-month periods. Each season starts on the first day of a month. When Each Season Starts in 2026

While meteorological seasons always start on the first of the month, astronomical dates vary slightly each year due to Earth's elliptical orbit. Meteorological Start Astronomical Start (2026) Significance Vernal Equinox; equal day/night Summer Summer Solstice; longest day Autumn September 1 September 22 Autumnal Equinox; equal day/night Winter December 1 December 21 Winter Solstice; shortest day Meteorological Versus Astronomical Seasons | News