There's nothing wrong with knitting mittens in August. In fact, it makes a lot of sense. It's a light, portable project that won't overheat you and it will give you warm hands in the winter; a winter which is coming sooner than we like to admit.
Confession. These are accidental full mittens. I wanted the quick satisfaction of a small project so I cast on Adorable Fingerless Mittens by Andi Satterlund. When I got to the palm of the first mitt it was clear that my gauge was way off and these mitts were far too loose. I also used the wrong yarn. The pattern uses sport weight and this Cascade 220, leftover from a sweater, is worsted.
Rather than chuck the project, I decided to just keep going and make traditional mittens. It was an easy modification to make and I am quite happy with the result so far.