this is related to the past , february also uses to have 30 days along with the other 4 months.the month july named after julius ceasar used to have 30 days in past but it was increased by one day and the balance was maintained by decreasing one day from february.the month august was named after augustis ceasar which had 30 days in past but was increased by one day and to maintain this balance one day from february was this way  , in present february has 28 days.
Earth is at perihelion during northern hemisphere winter. That means that winter has slightly fewer days than the other seasons, because earth is moving relatively fast at the time--from the winter solstice to the vernal equinox. Ergo, some winter month had to be shortened and it was February.