If you are worried that the hole in the canvas might get caught on something and tear further before you canvas this winter, a short strip of the good old all-purpose universal remedy -- duct tape -- might be applied. Stick it to the underside of the outwale as well as to the canvas, and it will keep out any splashed water and protect against any further ripping. I won't look very elegant, but for the short time you are talking about, it will give adequate protection for almost no time and effort.
Greg