So, you say you've got yourself a monster of a grill? We don't doubt that. If you've got your hands on one of the Weber Genesis™ II 600 series of gas grills, then you definitely have quite the beast.
The best way to keep that beast in working condition is to cover it up whenever you suspect Mother Nature is itching to release a storm. The cover is entirely UV and weather resistant to ensure a long life for the cover (and a longer life for your barbecue). To ensure your grill's safety, simply toss the cover on the grill and secure it down using the fastening straps.