Weather Whys: Why do we need a leap year?

Weather Whys: Why do we need a leap year?


2020 is a leap year and that means Saturday, February 29 is Leap Day! But why do we even need a leap year? Turns out the math is a lot more complex than you might think so we answer it in today's Weather Whys.

Many of us know that one year is equal to one revolution around the sun. At a young age you learn that a year is 365 days, right? Wrong. Technically one trip around the sun takes 365.2422 days. In order to compensate for the extra .2422 days we decided that every four years we would add an extra day.

So what would happen if we didn't add that extra day? We would miss about 5.8 hours each year which means that in ten years our calendar would be off by 24 days. That would mean Spring would start on February 25 instead of March 21. Crazy!

You can credit (or blame) our Leap Year system on Julius Caesar. He and his team discovered that the Roman Calendar of 355 days they used at the time was getting out of sync with the seasons. After doing calculations they discovered that a 365 day calendar was more accurate and they would add a day to the last month of the year which in the Roman Calendar is what we know as February. 

So we're all good, right? Julius Caesar fixes it all by adding an extra day every four years? Nope.

It took about 16 centuries to figure out that the seasons were off again so in 1582 Pope Gregory XII with his team of astronomers discovered that the Julian Calendar was 11 minutes too long so they added a slight change where a century year could only be a leap year if it was divisible by four, so 2000 was a leap year but 1900 was not and neither will 2100. This formed the Gregorian Calendar we use today.

The Gregorian Calendar is still not perfect. We still have an average of 25.9 seconds extra each year. But that's good enough for now since it would take 3,333 years for the calendar to get off by one day.

Weather Whys is a segment by Meteorologist Justin Thompson-Gee that airs during the CBS 58 News on WMLW - The M from 7 a.m. to 8 a.m. The segment answers viewer weather questions, explains weather phenomena and reveals interesting weather stats. To submit your question reach out to Justin on Facebook, Twitter or by emailing him at

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