In San Jose, California? So it "dropped" down to what, 68? Sorry you couldn't wear board shorts and sandals today...

Just kidding of course.

Living in Califorinia, you may or may not have heard of a space heater before. But either way, they are very effective for combating the occasional cold nights without doing a complete overhaul on the cage itself. Just put the space heater in the room with the cage to boost the room temp, and you should be fine.