Happy (First) First Day of Spring!

March 1st marks the first day of spring! Well… meteorological spring, that is. Astronomical spring isn’t officially until March 20th this year. Yes, it’s confusing, but there are technically two starts to spring. They’re usually 20 days apart too, which adds to the confusion because one day March weather can be cold and snowy, and 20 days later it can be warm and sunny. So, which one is the true start of spring? Let’s break down the difference between the two.

Meteorological Spring

Meteorological spring is always celebrated on the first day in March. Meteorologists and climatologists break down the year in groups of three months, with March, April, and May being the “spring” months. This system closely aligns with the annual temperature cycle and the calendars we use on a daily basis. According to the National Centers for Environmental Information, “By following the civil calendar and having less variation in season length and season start, it becomes much easier to calculate seasonal statistics from the monthly statistics, both of which are very useful for agriculture, commerce, and a variety of other purposes.” Makes sense, right? Well it’s not as straightforward when you bring physics into the equation, which takes us to astronomical spring.

Aleksander Kozlovskii via Unsplash

Astronomical Spring

Astronomical spring, otherwise known as the vernal equinox, is always celebrated on the day where the sun crosses the celestial equator from south to north. During the equinox, the length of day and night are nearly equal. It all has to do with the position of Earth relative to the sun, which in turn changes the length of the equinoxes (and solstices) each year. This is when a majority of people celebrate the start of spring, even though it could technically be seen as the second first day of spring.

So, is it a little premature to crack out the flip flops and pastel-colored clothes? Maybe. But whether you want to recognize the start of spring March 1st or March 20th, warm weather is on the way, and that’s enough reason for us to celebrate!