Why do i always get sick during the summer??!??!!?

now thanks to god. i dont get sick very often at all id say about once a year, but im 19 yearsold and ive noticed that i get sick every summer and its always just once like a fever atleast once in the summer. i dont understand or why? this always happens?! but it does--and i dont rly have any allergies or taking any medications, i take acne medication minocyline something like that but i know its not cus of that --like its so gorg. out right now and i have a freaking cold! and i think i might get a fever soon ....any anwsers as to why this happens? or how to prevent summer fevers? lol