Rig a tarp for your shelter from the rain, if you don't have a screened tent. By tying your tarp to trees, or using old tent poles to stake it up, you'll also have a makeshift shelter that will keep you and your food items dry. You'll be able to use your camping stove or grill to cook on, while you're protected from the rain. You'll probably need to place a pole in the center to raise it up a bit. This will allow the water to roll off the sides and not sink the center portion of the tarp.