I'm extremely paranoid when it comes to rabbits and hot weather.

My last bunny, Soup, had heatstroke once when she was about 5 or 6. The only tell we had is that she started being nice to us, but it was so out of character we rushed her to the vet where she promptly started seizing.

It was an hour between anything starting to seem off to getting her to the vets, and we were still almost too late.