No matter what, never try to cook with a grill inside a tent. Grills give off potentially deadly fumes that will stay trapped inside the tent. For that same reason, it’s not a good idea to put a dining fly over the cooking area. Hot air and fumes from a grill can get trapped under it, creating potential health and fire hazards. If the rain is a drizzle or light sprinkle, cover the food with the grill lid or aluminum foil and keep cooking. If it’s a downpour, it’s best to call it a day. Salvage what you can off the grill, shut off the gas grill or douse the charcoal, and get out of the rain.