My 7 year old gets a cough every year just after school starts that lasts for months. some days its mild others it's really bad. what could this be?

Could be Asthma!: The seasonal nature of this sounds suspicious for cough variant asthma to me. He needs a thorough history and exam by his pediatrician. I would try a trial of albuterol inhaler WITH a spacer for his cough to see if he responds. Does he have other allergies? Does he have seasonal itchy eyes? Does he cough with exercise? Family history of allergies/asthma (atopy, we call it)