Which month has only 30 days: March, April or May?
Month and days
When the Julian calendar was instituted by Julius Caesar, it was defined that the months would alternate between 30 and 31 days in order to comply with the solar year.However, this still didn’t match to the solar year, so one of the months would have to have only 29 days.But by that time, February was the last month of the year (not December), therefore it was the most logical to have one less day. From there on they just alternated the number of days sequentially.
One theory states that the reason why these specific months were chosen to have 30 days was that they were associated with Roman Emperors’ names, and the number of days would vary depending on the importance of the name. But this theory is most likely wrong.