Its not 28 but its 30 day

In the Gregorian calendar, February consist of 28 or 29 days. But three times in history, there has been instances where in some countries, the month has 30 days.

Swedish territory (which then included Finland), plans to replace the Julian calendar into Gregorian calendar began in 1700 to abolish leap day for 40 years. Therefore, 1700 is not a leap year in Sweden, but the years 1704 and 1708 are leap years beyond the plan. This leads to the Swedish calendar be a day faster than the Julian calendar but still 10 days behind the Gregorian calendar. Confusion is reduced when in the year 1712, two days intercalary added, has resulted in the 30 February. The same day in the Julian calendar February 29 and 11 March in the Gregorian calendar. Substitution of Sweden to the Gregorian calendar finally done in 1753.

In 1929, the Soviet Union introduced a Soviet revolutionary calendar in which every month has 30 days and the remaining 5 or 6 days does not form part of any month and a day off. Therefore, the years 1930 and 1931 have a turnover February 30 but was canceled in 1932 so again following the normal calendar.

Sacrobosco, a scholar of the 13th century claim that the Julian calendar February had 30 days in leap years from 44 BC to 8 AD when Emperor Augustus memepersingkat February to August, which is called by its name has a length equal to the month of July (which named after his predecessor Julius Caesar). Yet there is no historical evidence about it and most likely this is just an old myth.