Each guest can bring up to two animals to the Repticon show's, but you are responsible for your animal and it must be in good health otherwise they may ask you to leave the show. That's directly from their FAQ page. I've brought my snake to the shows before, but I didn't let anybody hold her, and I kept her away from other snakes because you never know what kind of health they're in. As long as you do that you shouldn't have to quarantine your snake again. So yes you can bring your snake, just bring a pillow case in case your snake decides to start trying to bite you or somebody.
I checked the temps for Baltimore, MD for tomorrow and it says 79° which is fine for your snake because they'll be wrapped around your arm or wrist, or neck(if it's a BP). They will absorb your body heat so they will be fine. If anything I'd bring a long sleeve shirt and if it does happen to be cold inside where the show is you can let your snake wrap around your arm under your sweater which will create a hot space for them.