People or other pets can bring fleas into pet owners' homes, and any outdoor exposure may increase a cat's risk for fleas. Fleas can survive a winter if temperatures are not cold enough, or they find a warm barn, garage, house or pet to live on for the winter. The bottom line is, it is important for cats to have monthly flea protection year-round. Advantage II controls against all flea life stages and kills through contact. Fleas don't have to bite to die.