Leaving your convertible out in snow for extended periods of time can be harmful in some ways, even with the roof up. A car cover is essential in this case, but if you don't have one on hand, make sure you brush accumulated snow from the roof with a soft brush as often as possible. The weight of heavy snowfall can be damaging to the fabric cover and the frame that supports it, so beware of leaving your soft-top convertible unprotected in the winter.