We won't have another leap year until 2020, but that doesn't mean we don't have February's bizarre relationship with Father Time on the brain now. You're probably already aware that February is the only month in our calendar year that actually fluctuates in length (it's 28 days long during regular years and 29 days long during leap years). But this is just the latest entry in the strange history of people messing with how long the second month of the year is.
February as we know it in our own Gregorian calendar came into being in ancient Rome, when the Romans added January and February to their 10-month-long calendar in order to sync up with the lunar year of 355 days. Up until then, there hadn’t been any months at all assigned to the wintertime (which we’d personally interpret as the Romans’ efforts to forget that winter exists). After that, February was 28 days long, but that would soon change.
It soon became apparent that the 12-month Roman calendar was still out of step with the seasons, so they came up with a delightfully confusing system to address that issue. Now, stay with us. Every other year, a brief month, lasting between 22 and 23 days, would be inserted into the calendar to catch up with the solar year (which is 365 days long). This month was known as Mercedonius and — here’s where it gets weird — it occurred between February 23 and February 24. It probably comes as a surprise to no one that this system didn’t last long.
In fact, the only reason we have the leap year system we know (and scratch our heads over) today is because that’s what Julius Caesar came up with to replace Mercedonius. At its heart, it’s still a desperate grab to keep up with the solar year.
If we had to guess why people always targeted February with these changes, we'd blame its overall vibe. The midpoint between the winter solstice and vernal equinox (which you might know as Groundhog Day) lands in early February, and this month's full moon has long been associated with the first signs of spring, or the quickening of the seasons. In other words, Nature spends the month of February hinting at all the big seasonal shifts to come. Why wouldn't we want to speed up — or at least shorten — that process and get to spring already? Maybe the winds of winter have clouded our reasoning, but that's our best guess.