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The first of March marks the start of spring for meteorologists in the Northern Hemisphere, even though astronomical spring comes much later in the month on the spring equinox. Meteorologist Caitlin Kaiser explains the differences between the two and why meteorologists follow a different seasonal calendar.

Why it matters

The distinction between meteorological and astronomical seasons is important for weather forecasting and reporting, as it allows meteorologists to better track seasonal trends and patterns that may not align with the astronomical calendar.

The details

Meteorologists define the seasons based on the annual temperature cycle, with spring running from March 1 to May 31, summer from June 1 to August 31, fall from September 1 to November 30, and winter from December 1 to February 28 (or 29 in a leap year). This differs from the astronomical seasons, which are based on the Earth's position relative to the sun and the spring equinox, which typically falls around March 20-22 each year.

• March 1st marks the start of spring for meteorologists in the Northern Hemisphere.
• The spring equinox, which marks the astronomical start of spring, typically falls around March 20-22 each year.

What they’re saying