When Julius Caesar established the Calendar, seasons began on 25th. I just don't know why he decided it to be so. March is devouted to pagan idol Mars, the Roman g-d of war, that's why it was the beginning of the year, since it was the beginning of Roman military campaigns. April (Aprilis) means "to open" and remembers Spring when flowers "open" (bloom). When Julious Caesar established the Calendar (based on Egiptian calendar) and added January and February, he decided to begin the years on Jan the 1st, so he had two months to plan military actions.
Untill the Julian Calendar was established, most nations used lunar calendars (except Egipt).
Generally lunar calendars had a leap year of 13 months to avoid seasonal drift, just as Jews and Chinese Calendars. Arabs also used lunar leap years before Islam, but then Muhammad forbade the leap month since " we, Muslims, can't even read....how can we claim to know when to add a month?!!!!"