The United States experiences epidemics of seasonal flu each year. This time of year is called "flu season." In the United States, flu season occurs in the winter and flu outbreaks can happen as early as October and can last as late as May. Flu seasons are unpredictable in a number of ways. While flu spreads every year, the timing, severity, and length of the season varies from one year to another. Lear more today how you and family can prepare!