How Meteorological and Astronomical Seasons Are Different

As a self-proclaimed weather nerd with some education to back it up, I occasionally get some interesting questions. The other day on air, I mentioned that the meteorological summer starts on June 1, while astronomical summer starts on June 21.

Over the weekend, someone stopped me and asked, “What’s the difference, and why don’t meteorologists use the astronomical calendar?

It’s a great question, and the answer comes down to how meteorologists and climatologists view the entire calendar year and the data they collect.

Meteorological Seasons

“Meteorologists and climatologists break the seasons down into groupings of three months based on the annual temperature cycle as well as our calendar,” said the National Centers for Environmental Information.

Another way to look at it is that the meteorological seasons coincide with the annual temperature cycle. “Think of winter as the coldest time of the year and summer as the warmest time of the year, with spring and fall being the transition seasons.”

For a more scientific take on the subject, the National Oceanic and Atmospheric Administration said, “The length of the meteorological seasons is more consistent than the astronomical seasons, ranging from 90 days for winter of a non-leap year to 92 days for spring and summer.”

This also means that the various start and end dates in the astronomical calendar make it hard to keep climatological statistics for a season over time.

• Meteorological Spring: March, April, and May
• Meteorological Summer: June, July, and August
• Meteorological Fall: September, October, and November
• Meteorological Winter: December, January, and February

Astronomical Seasons

The astronomical season dates vary from year to year based on Earth’s position relative to the Sun as it travels in its yearly orbit. The solstices mark the year’s longest and shortest days, while the equinoxes occur when day and night are equal.

“Because Earth actually travels around the sun in 365.24 days, an extra day is needed every fourth year, creating what we know as Leap Year. This also causes the exact date of the solstices and equinoxes to vary,” said the National Centers for Environmental Information.

Northern Hemisphere 2026 Dates

• Spring Equinox: March 20
• Summer Solstice: June 21
• Fall Equinox: September 22
• Winter Solstice: December 21

Thanks again for the great question about meteorological versus astronomical seasons. Again, I’m a weather nerd, and I love digging into questions like this.

If you have other weather-related questions, I’d love to hear from you. Feel free to stop me when you see me out and about, or email me at maryk@townsquaremedia.com or send a message to our app.

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