Good luck but the northernmost Windmills on the east coast to have lasted any significant amount of time are around Rehoboth Beach and Cape May NJ, and the only to have lasted a really long time around Virginia Beach and Hampton. So, roughly 1000 miles south of the southernmost point of Newfoundland! Even Martha's Vineyard has been below 0F, and quite recently, too. St. John's average HIGH in winter is < 32F/0C. That's really going to suck the life out of even the hardiest palms. Years ago a guy in the mountains of Colorado did very scientific experiments on keeping Trachys alive and the time factor below freezing was a major player, along with seasonal record low. Because the palms can't be metabolically active below freezing.

I'm guessing if it was made for outdoors that they've tested it for that environment and would warn you otherwise. Of course, you can't count of that. My mom has a plastic tablecloth for her dining room table and the underlining is a thick flannel type material. It's used under a regular tablecloth, but its purpose is so you can set hot casseroles, etc. on it without damaging wood. Wonder if something like that would work in conjunction with normal patio table cover? Just to help isulate it? I agree you may want to leave an air gap. Just throwing that out there....

These cleaning instructions were listed under the Sunbrella brand of fabric. Outdoor Fabrics, Floral Fabrics, Cleaning Code Most stains on Sunbrella fabrics can be cleaned up with a mild soap and water solution. · Spot wash by sponging briskly with a solution of natural soap in lukewarm water. · Rinse thoroughly with clean water to remove soap, then air dry. · For stubborn stains, use fabric spot remover. Follow the directions on the container. · For removable cushion covers, machine wash in cold water with a mild soap, then air dry. · Sunbrella acrylic does not promote mildew growth. However, mildew may grow on dirt and other foreign substances that are not removed from the fabric. To clean mildew stains, prepare a mild solution of one cup bleach and two capfuls of natural soap per gallon of water. Spray on entire area and allow to soak in. If necessary, scrub vigorously with a sponge or clean rag. Sponge thoroughly with clean water, then air dry. You might be able to find your fabric with the fabric finder search tool. Hope that helps! Here is a link that might be useful: Greenhouse Fabrics

You're the second person to bring up this topic, someone else asked about this not that long ago. So I'll tell you what I told her....I use covers made by Classic Accessories for all of my patio furniture and I am very happy with the quality. I recommend their Veranda line not the Terrazzo. When the weather turns dry I pack them all up in a large toter we keep along the side of the house and I bring out the towels for the summer. That may sound anal but I hate sitting down on dusty/dirty cushions so the towels are perfect for that and they're lightweight enough that I can toss them aside very easily. Doesn't matter to me that the Veranda covers are more substantial because I'm not taking them on and off during the months we're using the patio. I suppose if you live in a part of the country where it rains all year round, even in the summer than removing bulky covers could become a nuisance. Dirt doesn't get into either of my deck boxes. For the smaller cushions (ie. not the long chaise lounge size) it's cheaper to buy 50 gallon toters from Rubbermaid. The only place I've seen them in that size is Home Depot. You should see the side of my house, it's lined up with 2 deck boxes and super size toters (stacked 2 and 3 high!) to store cushions, covers, pillows, and holiday decorations. Never had a problem with water getting inside and I would know because several of them hold my collection of Dept 56 boxes and that flimsy cardboard has no tolerance for moisture. Here is a link that might be useful: outdoor furniture covers