What kinds of temperatures can rats withstand?

I have my rats in my garage. A cold front is coming through and its about 55 degrees outside. But in my garage is around 60-62. I know temperatures can effect breeding, but right now I don't need anymore food for the snakes (I have a ton in my freezer) so I have them all seperated. I'm just concerned for their health.

Is this too low? Should I put a heater in there?

The temps in my rat room fluctuates between 48 and 80.

Never had any health issue.

As far as production my colony does best between 68 and 73.

Thank you. Makes me feel a lot better.