Unless we’re talking torrential downpour (and even then, even the most hardy will still brave the elements to fire up the grill), you can still grill when Mother Nature seems to have it out for you. For many, this just means throwing on a parka or raincoat and just grilling as you would normally but I have a few suggestions (and some warnings) that might make for a better grilling experience.
Get some cover if you can. If you can get a large umbrella or some other covering for your grill, it’ll help your grill maintain temperature when the cover is closed. The rain hitting the grill won’t be 300 degrees, so each drop will cool the the temperature of your grill and start messing with the cooking times. Very heavy rain can leak in and even overflow your grease tray, depending on how your grill is configured.
Monitor cooking times. Since the rain will reduce how often you’ll want to be outside, it’s easy to burn things on the grill when it’s raining heavily. Since you’re trying to reduce the number of times you’re opening the grill, you run the risk of leaving things on too long.
Don’t let the grill go out of your sight. Grilling in picturesque weather and grilling in rain is the same, you’ll want to keep an eye on it so nothing bad happens. A grease flareup can happen just as easily in the rain! (and can be made worse!)
Be careful about air flow. If you do have cover, make sure you have sufficient air flow so that the smoke and carbon monoxide have somewhere to go. The last thing you want to do is get lightheaded and fall onto your grill.
Be careful about high winds. Rain is often coupled with wind and if you have a light grill, say a charcoal Weber One Touch, you have to make sure heavy winds don’t blow your grill over. You can use weights to keep the legs stable or just skip grilling until next time.
