It's a tough call, it depends on how warm your garage is. Personally, I would leave them outside and just pile dirt/mulch/hay around the pots to help insulate them. Hops are tough and handle the cold reasonably well, even the shoots typically survive overnight freezing temps. You can check this weather data for Yakima Washington, the average low temp is below freezing for 4 months (but it warms up during the day).http://en.wikipedia.org/wiki/Yakima,_Washington
depends on where you live in Colorado and what your weather is like. If they're going to be under a couple of feet of snow I would not worry about them at all. But you said it is dry, so I'll assume exposed ground. It would be tempting to bring them in somewhere if it were going to get absurdly cold for long periods of time, but if it's only going to get down to 20 or so overnight I would leave them outside. Maybe put them all together with some bales of hay around and covering them to protect them from the coldest winds.
If you have an inside area you can keep them that will be warmer but still under 40, that would be good I think. Otherwise if they get too warm they might start sprouting in your garage. As for watering or dry in your garage - they shouldn't need much water when they are dormant, so I would water only very minimally. Although it certainly rains for months on end in the Seattle area during the winter, and the hops come up every year, so I wouldn't worry about it too much.