So what’s the difference? Meteorological spring describes the season in a very tidy way: by looking at it as just the months of March, April, and May. Compare this to astronomical spring – aka the vernal equinox, when the sun is directly above the equator – which traditionally indicates the first day of spring. This date can vary from March 20-22, depending on the year. This year, the vernal equinox will be on March 20!

Since the exact timing of the vernal equinox varies, the length of a season varies, too – by as much as five days. That makes it hard for folks who study weather to make year-to-year comparisons of seasonal conditions, so they created the concept of meteorological spring. Both are valid, so you celebrate one or the other or both. We love spring, so we do both!