Bungees are quite handy.My Weber Performer Deluxe cover only has velcro at the bottom of one single side. Even then, it's only long enough to close around the leg above the bottom wire shelf. So when a strong wind comes from underneath, the cover does a Marylin Monroe. Every now and then, the wind blows it off the cart completely and the only thing preventing it from flying away altogether is that single velcro wrap.
I think I'm going to sew additional and longer velcro strips on 2 more legs diagonally across from each other.