What you can do is give them an insecticide treatment, leaves and medium, so that you won't be bringing any unwanted critters into the cozy house. They'll think their in Hawaii and multiply like crazy.
Do it a couple of times, a week apart.
I live in Pa and have brought all my orchids in except for a dendrobium. It would be helpful if you tell us what you have, but as long as there is air movement and is only going to be tonight, you should be fine. In terms of watering and fertilizing, it depends on the plants. Instead you should start slowly transitioning the orchid to the winter culture. Good luck.