Well, it looks like our bunnies hit their max temp today. The thermometer outside was reading 98 degrees when I got home. DH had put a frozen water bottle in with them around noon. Their hutch is in the shade. The water bottle was still cold when I got home at 4. However, the girls were laying next to it, panting and didn't even move when I opened the door to the hutch. (whever I approach the hutch, they usually start running in circles) I scooped them up and brought them into the house. They are now in our family room in an xtra large dog kennel with a litter pan. It took some time, but they look much calmer now and have been up and sniffing around exploring. I thought DH would freak when I told him I brought them inside but he has grown attached to them too. I don't want to keep them in my family room, so we are working on our backup plan this weekend. Luckily, the temps are going back down to the 80's this weekend before they start climbing back up again. It amazes me how much chickens and bunnies have changed my attitude (for the better !) over the past year and half.
I use a fan in the hotter months. I also use frozen bottles and the fan blows on the bottles. The bunnies lie behind the bottles so it is sort of like outside air conditioning. It gets very hot and humid here for months and they have done well with that. Their hutch is also under a big oak tree.