Spring 2021 starts on March 20th, unless it started on March 1st.

“Happy first day of Spring!” A coworker said to me, and she wasn’t the first one to say it. I looked outside, it was snowing. It had snowed almost everyday since November. What were these people thinking? This was not Spring.

That was me on March 1st, 2006. At the time I was living in Ukraine where the winters were long and harsh. I felt like my co-workers were engaging in some wishful thinking by declaring the first of March to be the beginning of Spring. I would consider calling it Spring on the equinox.

Cut to 2021. I’m living in St. Louis, MO with its milder winters. After a bad cold snap in February the weather started to warm up. When March 1st hit I started saying it was Spring. However a certain highly opinionated kindergartener took issue with this. She had it on good authority that it was not Spring yet, and she would not be persuaded otherwise.

Was I right in the past or am I right now? Well it depends on how you define Spring.

When we think of the “official” start of Spring we are generally thinking about astronomical seasons, which are based on how the Sun is hitting the Earth. The reason we have seasons at all is because the Earth sits on a 23.5 degree angle. We get more sun in the summer and less in the winter. In Australia they go to the beach for Christmas because the seasons (and movement of shadows) are reversed in the Southern Hemisphere.

Day and night are about equal on the Spring Equinox (also known as the Vernal Equinox), but that’s not what the day signifies. Where I live the Spring Equinox will happen on March 20th at precisely 4:37am. That’s the time when the Sun will cross the equator. After this point the Northern Hemisphere will be tilted more towards the sun.

The Sun will appear higher and higher in the sky until June 20th at 10:32pm. That’s the Summer Solstice, the longest day of the year and the start of astronomical summer. That is, unless you’re in the Southern Hemisphere, in which case June 20th is the Winter Solstice, the shortest day of the year and the start of astronomical winter.

The equinoxes and the solstices don’t always happen on the same day for the same reason we have leap years--the Earth doesn’t quite make it all the way around the sun in 365 days. It takes 365.24 days to go around the sun which alters when the equinoxes/solstices occur.

That inconsistency in dates is part of the reason meteorologists don’t go by astronomical seasons. In order to be able to accurately compare weather data from year to year, meteorologists break down the seasons like so:

Winter: December 1st - February 28th/29th

Spring: March 1st - May 31st

Summer: June 1st - August 31st

Fall: September 1st - November 30th

There is another reason meteorological seasons are different from astronomical ones: they tend to be a better reflection of the weather. In most of America the coldest days of the year are December through February, not in March.

So do I go by astronomical or meteorological seasons? Well, neither really. There are other ways to define seasons, but I don’t really find them satisfactory either. Labels can be useful for understanding and describing the world around us. However, mother nature doesn’t really care about our labels and doesn’t conform to our rules. And I think it’s silly to say that winter ends on the same day in Alaska as California. Plus there’s the issue that the summers are getting longer.

When does Spring start? Well, I would say when it feels Spring-ish.

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