Season Dates 2025. The 2025 big ten college football schedule was unveiled on wednesday. Summer 2025 starts on friday, june 20th in the northern hemisphere, with the first day of summer being the longest daylight day of the year with the earth's axis having reached its furthest tilt and begins to change.

Fall begins with the autumnal equinox, monday, september 22,. Since the seasons vary in length, the start date of a new season can fall on different days each year.