You should be able to find a relatively inexpensive ($40-50) zippered canoe cover that will fit your kayak. Not only does it protect from the sun/UV rays, it also keeps the dirt, pollen, mold, bugs etc. off to keep your boat nice and clean. (Sportsman's Guide carries a couple of inexpensive brands.) I use these year-round and all my boats stay looking great.
Kayak & Canoe Covers
Kayak Motor Kit