Why does February only has 28 days?

February is wrapping up. It is a short month because it is “missing” days, but why does this month only have 28 days (or 29 in a leap year) instead of 30 or 31 as the other months do?

The reason can be found looking back in history to the time of the Romans. At that time the year had 10 months called Martius (March), Aprilis (April), Maius (May), Iunius (June), Quintilis (which became July), Sextilis (later becoming August), September October, November and December. In this calendar, months alternated with having 30 or 31 days in a year totaling 304 days. The others were simply winter days in which there was nothing worth celebrating, no agriculture or production and in short, were just considered unimportant.



It was the king Numa Pompilio in the year 713AD who decided that in order to adapt the calendar to the lunar one a further 2 months would need to be added. They were inserted at the beginning and the end of the year and were called Ianuarius (January) and Februarius (February) as the time of purification and the year ended up with 354 days.


The number of days in each month was also changed. At the time of Numa Pompilio, it was believed that even numbers were unlucky, so to remain in favor of the Gods, the calendar was modified to alternate months with 29 or 31 days, but the numbers didn’t add up. So, as January and February were fallow months he considered it not to be a problem in giving one of them 28 days.
However, nobody liked that the year began with an unlucky month. A day was added to January so that it would have 29 days. Equally this did not work as dates were not corresponding to the four seasons. Over a period of time days were added every few years but no one could ever agree in how many should be added.

This changed during the time of the Republic when Februarius was established as the first month and it was decided to add a new month called Mercedonius every second year. This too was not a popular solution.

Julius Cesar, the famous Roman military and political leader was the one who finally put order to the calendar. After consulting with the astronomer Sosigenes of Alexandra he came up with a far simpler solution. He returned Ianuarius back to being the first month, played with the even numbers that were not unlucky (which led to months having 30 and 31 days) and regarding February, he felt that 28 days for purification would be enough. The resulting calendar did not adjust completely to the movements of the sun, so this problem was solved by adding a day to Februarius every four years.

You can read the full article here.