The start and end dates for the four seasons depend on whether you use the astronomical (sun-based) or meteorological (temperature-based) calendar. The Old Farmer’s Almanac Northern Hemisphere Dates (2026)
For most people in the Northern Hemisphere, the official "first day" of a season follows the astronomical calendar, though weather experts use fixed monthly dates for better data tracking. Time and Date Astronomical (Sun Position) Meteorological (Calendar) March 20 – June 20 March 1 – May 31 June 21 – Sept 21 June 1 – August 31 Sept 22 – Dec 20 Sept 1 – Nov 30 Dec 21 – March 19 (2027) Dec 1 – Feb 28 (2027) Why Two Different Systems?
Seasons of the Year: When Do They Start and End? - Time and Date
The dates of the four seasons depend on whether you are looking at the calendar through the lens of astronomy or meteorology. 1. The Astronomical Seasons
Most people are familiar with the astronomical seasons, which are based on the Earth's position relative to the sun. These start and end on specific "turning points":
Spring (Vernal Equinox): March 20 or 21. This is when day and night are roughly equal in length.
Summer (Summer Solstice): June 20 or 21. This is the longest day of the year.
Autumn (Autumnal Equinox): September 22 or 23. Day and night are equal again.
Winter (Winter Solstice): December 21 or 22. This is the shortest day of the year. when do the four seasons start and end
Because the Earth takes about 365.24 days to orbit the sun, these dates shift slightly each year, which is why we have leap years to keep them from drifting too far. 2. The Meteorological Seasons
Meteorologists and climatologists use a different system. They break the year into four three-month periods based on the annual temperature cycle and the Gregorian calendar. This makes record-keeping and data comparison much simpler. Spring: March 1 to May 31. Summer: June 1 to August 31. Autumn: September 1 to November 30. Winter: December 1 to February 28 (or 29). 3. The Hemispheric Difference
It is important to remember that these seasons are reversed depending on where you live. When the Northern Hemisphere is tilted toward the sun (Summer), the Southern Hemisphere is tilted away (Winter). Therefore, while a New Yorker is starting their summer on June 21, someone in Sydney, Australia, is beginning their winter.
In short, if you follow the stars and the sun, the seasons begin around the 20th–22nd of the month. If you follow weather patterns and the calendar, they begin on the 1st. Both systems provide a useful way to organize our lives around the natural rhythm of the planet.
The start and end dates of the four seasons depend on whether you use the astronomical
definition (based on Earth's position relative to the Sun) or the meteorological
definition (based on the calendar and temperature cycles). Because Earth is tilted, seasons are reversed between the Northern and Southern Hemispheres. The Old Farmer’s Almanac 2026 Seasonal Dates
For the year 2026, the specific astronomical transitions are as follows: Northern Hemisphere (Astronomical) Southern Hemisphere (Astronomical) March 20 – June 20 September 23 – December 21 June 21 – September 21 December 22 – March 19 (2027) September 22 – December 20 March 20 – June 20 December 21 – March 19 (2027) June 21 – September 22 Two Ways to Define Seasons Astronomical Seasons : These are defined by (when day and night are roughly equal) and The start and end dates for the four
(the longest and shortest days of the year). These dates vary slightly each year because the Earth takes about 365.24 days to orbit the Sun. Meteorological Seasons
: Used by scientists for consistent record-keeping, these split the year into four 3-month periods that always start on the first day of a month. Northern Hemisphere
: Spring (March 1), Summer (June 1), Autumn (Sept 1), Winter (Dec 1). Southern Hemisphere
: Spring (Sept 1), Summer (Dec 1), Autumn (March 1), Winter (June 1). The Old Farmer’s Almanac The Role of Earth's Tilt
Seasons of the Year: When Do They Start and End? - Time and Date
There are actually two different ways to define the seasons: the Meteorological method (used by scientists and weather forecasters) and the Astronomical method (based on the position of the Earth relative to the sun).
Here is the breakdown of both.
Meteorologists and climatologists use fixed calendar dates for simpler record-keeping and forecasting. These seasons align more closely with the annual temperature cycle. The dates are fixed and do not vary by year. Spring: March 1 – May 31 Summer: June
Winter begins on the shortest day of the year (in the Northern Hemisphere).
If you are a gardener, a farmer, a utility company planner, or a public health official, the astronomical seasons are frustrating. Why? Because by the time the winter solstice arrives on December 21, it has already been cold for weeks. Conversely, by the summer solstice on June 21, the hottest weather is often still a month away (due to seasonal lag).
To solve this, meteorologists (and many climatologists) created a simpler, more practical system based on the annual temperature cycle. They split the year into three-month blocks that align with our sensory experience of weather.
Astronomical seasons are defined by the Earth’s position relative to the Sun. Their start and end dates vary slightly each year (usually by 1–2 days) due to the leap year cycle.
Note: In the Southern Hemisphere, the astronomical seasons are reversed (e.g., their summer starts in December).
🔥 Solstice = longest/shortest day of the year.
The concept of seasons is based on Earth’s axial tilt and its orbit around the Sun. However, there are two widely accepted systems for marking the boundaries of spring, summer, autumn, and winter: the astronomical seasons (dependent on solstices and equinoxes) and the meteorological seasons (based on annual temperature cycles and the calendar).