CLEVELAND — You may be double and triple checking the date because typically the start of Spring is on March 20th or 21st. In fact, this will be the earliest start to Spring in the Northern Hemisphere since 1896 (…124 years!). So this naturally begs the question, why is Spring so early this year?

Well…it gets a wee-bit complicated…but the long and short of it is that is has to with our rules with time and leap years (adding an additional day to the end of February – the 29th). As you know, every 4 years, we add an additional day to the end of February with one exception. This is where it gets interesting!

Rules with Time/Leap Years:

  • If a year is divisible by 4, it is a leap year. However…
  • If it is a Century Year, it will NOT be a leap year. However…
  • If that Century Year is evenly divisible by 400, then that Century Year is to be a leap year.

Interesting – right!? Let me show you a couple of instances so it makes more sense…

So for example - the years 1700, 1800 and 1900 are century years, but not evenly divisible by 400, so they were NOT leap years.

  • 1700/4 = 4.5
  • 1800/4 = 4.5
  • 1900/4 = 4.5

Now, when we get to the year 2000 – *GASP* – it’s evenly divisible by 400!

2000/4 = 5

So this means the year 2000 WAS a Leap Year! This “century year evenly divisible by 400 will be a leap year” rule happens every 4 centuries. Awesome! What this means is that every leap year to come, so in 2024, 2028, 2032, 2036, etc. we’ll set a new “record earliest Spring!” until the next century (…because the year 2100, is not evenly divisible by 400, it will not be a leap year. [2100/400 = 5.25]). Given that 2100 is not divisible by 400, it will not be a leap year, and the start of Spring will get pushed back to the 20th or 21st of March because we won’t have that extra calendar day of February 29th in 2100.

Thank you for allowing me to completely and totally geek out with you!

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