Chiminea Cover - Protection for a Longer Life
As an example, their large chiminea cover is good for a chiminea with 60" circumference and 54" tall. The oversized one is good for one that is up to 80" circumference and 54" tall. A small to medium cover that measures 42" in height would probably satisfy coverage of a typical chimnea that is 42 inches high or less.
Circumference is another question, and not all covers tell you up to what circumference the cover will fit.
Look for one that is UV resistant (most are) otherwise the life expectancy isn't great, as the cover will likely start to crack. Also shop for a material that is durable like vinyl or a pvc material. Many come with a drawstring at the bottom for a snug fit and to stay in place. If the sizing is off a little, you can always figure a way to fit it.