Looks like weather for Miami game will be fairly typical for South Florida in mid-September.
Hot (around 90)... Extremely humid...
And good chance of crazy heavy thunderstorms coming through at any moment (or not), although typically mid-late afternoon.
So dress light... bring sunblock or you'll be toast by halftime (even if it's cloudy)...
And if you like, be prepared for super heavy rain during or after the game (even if it's clear blue skies during the tailgate). Maybe a small foldup poncho or a large black garbage bag.
Or rough it and get soaked. Doesn't matter to me. Just sayin.
National Weather Service details here: