You're in an area where small hive beetles thrive. Hives in full sun have fewer beetles. The bees can live with the heat much better than they can tolerate multitudes of small hive beetles. You can ventilate by propping the outer cover open and using screened bottom boards and be sure they have a water supply nearby. Use a weedeater near the hives and a mower a little further away. The bees will let you know if you need a veil.