Part of what I found from a news source:
It's because of ancient Roman history that Leap Day falls in February.
"It's mostly that the Romans didn't really like February very much," Ben Gold, a professor of astronomy and physics... At the time, in the 8th century BC, the calendar was just 10 months long, with the Romans considering winter to be all one period not divided into months. Eventually, the Romans established January and February. February, the final month, had the fewest days.
Julius Caesar then adjusted the calendar to line it up with the sun, Gold explained, adding Leap Day via decree. That still didn't fully account for the difference in time, though. That wouldn't be fixed for hundreds more years.
In 1582, Pope Gregory XIII adopted the Gregorian calendar, which we now use, and specified that all years that can be divided by four are leap years, with the exception of century years, which would have to be divisible by 400 to be considered leap years – so while 2000 was a leap year, 2100 and 2200 will not be.
In the 1700s, British law designated Feb. 29 as Leap Day.
The Romans didn't "like February very much." Ha!
