The odds of a hurricane causing an evacuation in the first week of July are very low.
Pretty much any comprehensive travel insurance policy will cover a mandatory evacuation caused by a hurricane, so you should be fine to shop on price. I'd review the options at InsureMyTrip.com - they offer a wide-array of policies with all sorts of different coverage parameters. Again, since your goal is storm coverage, don't pay extra for coverage you don't care about. A more expensive policy isn't going to get you "better" storm coverage.
Also, check the policies you are considering, but since you're primarily concerned about weather related events, you can usually wait and buy insurance at the last minute if you think it's going to be necessary. For most policies, the only requirement is that you purchase the insurance before the storm is named. Named storms don't normally pop-up without ample warning, so if you see a Tropical Depression or Potential Tropical Cyclone being tracked by the National Hurricane Center in the week before your vacation, then you can consider taking a flier on the insurance.
I vacation in mid/late August and usually end up buying the insurance, though, knock on wood, I've never needed to use it.