In the United States, spring begins in March. In the meteorological calendar, spring starts on March 1 and runs through May 31, making March the standard answer for a month-based trivia question.
There is another widely used definition: astronomical spring begins at the March equinox, which usually occurs on March 19, 20, or 21 in the Northern Hemisphere. The equinox is the moment when the Sun crosses the celestial equator, bringing nearly equal daylight and darkness around the world. Its exact date and time vary from year to year because Earth’s orbit does not fit perfectly into a 365-day calendar.
The two systems are not contradictory; they serve different purposes. Meteorologists use fixed three-month seasons to compare weather and climate data consistently, while astronomers define seasons by Earth’s position in orbit. A common mistake is answering June, because June begins summer in the Northern Hemisphere. In the Southern Hemisphere, March marks the beginning of autumn instead.