Some historians believe February always had 28 days ever since the time of King Numa Pompilius. He decided that a year would have 355 days, the length of 12 lunar cycles. Back then, even numbers were considered unlucky. So, he created seven months with 29 days, and four with 31. Since he now needed one short even-numbered month, he chose February, as it was considered the least favourite month for it arrived during the middle of winter. And hence, it was given only 28 days.