Living in Florida, I totally know your concern. After Irma our neighborhood lost power for about two weeks (seriously, what the heck electric company). It was
extremely stuffy inside the house, so unless it was time for food I had parked myself in the backyard.
I would have to say what I would do. During Irma, about anywhere between 10am and 1pm we lost power. There goes the lighting and heating. I would keep the lizard inside the tank (to soak up any leftover heat from basking areas) unless you need beardie cuddles. The days after the hurricane, go outside with your lizard and plop him down somewhere in the sunshine. He'll be receiving natural UV rays and might like having a little adventure. If you're worried about him wandering off, you could buy a lizard harness, but I think those things look ridiculous. Just keep a close eye on him, taking him out regularly. I think a bearded dragon will be fine doing this for a short period of time.