I have a couple of covers that cover the A/C only. They will stay on at 70 mph into about a 20 mph headwind. Verified by experience. If I get worried about snow before we leave, I will cover the A/C units and leave the covers on until we get down South. Covering the A/C units was suggested by our RV dealer/service shop in the event that we do not put the full cover on. Tried taking the full cover off with about 4" of snow and ice on top. Postponed our departure a couple weeks so the sun could melt the stuff off of the cover. Go south every year now so no longer use full cover.