I hear y'all on the lightning, not safe at all to be on the water during an electrical storm...BUT! Typical Summertime thunder storms happen during the afternoon after the sun has heated the clouds.
If you can drag your butt out of bed and get on the water by first light, you can usually get in a few hours of good fishing without the worry of lightning... even if it is raining. This is also a good time to go on the weekends because the knuckleheaded jet skiers and water skiers are still passed out in bed. You'll most likely have the whole lake to yourself for a few hours. The lake or river has calmed down overnight from the boat traffic the day before and the fish are more willing to bite. Fishing in the afternoons is mediocre at best this time of year on crowded lakes.
Now about that rain, I would gladly trade the blistering hot and near drought conditions for a couple weeks of rainy weather with cooler temperatures... anybody wanna swap?