I've got something like that from Ebay, and I take my ipad even to the beach!
Leather case works for me but I don't carry mine while on foot in heavy downpours. It's enough just to keep the iPad dry when going between the car and whereever I am or am going to. If you need serious protection then get suitable carrying gear for it whether it's a waterproof sleeve/case or a waterproof bag for your stuff that you can toss it into. There are plenty of options out there and it's up to you to determine which is best suited to you.What does everybody here use to carry the iPad on a wet day? Is a leather case enough or do you take a plastic bag?