Someone explain my random sneeze attacks...?

Sometimes when going from outside to inside or vice versa, or when the seasons start to shift, I have these horrific sneeze attacks out of the blue. Out of nowhere I'll get a tickle in my nose and have to leave the room and go sneeze about 25-30 times before feeling better. I am congested for the rest of the day until I wake up the next day feeling better, and wondering what happened. What is going on here? What are the best remedies for this?, especially when I feel an attack coming? Thanks!