OP, I don't have the time to explain everything, but so long as you are confident your operation won't go down, the only thing that may have a problem with temperature delta is the PSU. The heat generated from the miners will be more than enough to keep condensation off, though... So I'd say go for it, just have a spare Psu in case... But I have all of my miners outsideand I've never had a problem, two of them reside on my balcony, in fact.
I've had a similar experience. I kept a few in garage last Winter with a door open and had no problems. The garage is slightly warmer than outside, while area around mining rigs is warm, and of course inside the cases is quite hot, so as long as humidity isn't 100% and we just recovered from a long power outage, chance of critical failure is pretty damn low. I suppose a power outage with a large operation and a low-R ceiling/roof with certain other conditions could actually form rain clouds in a building (or maybe at least fog)... that'd be really cool. It'd ruin a lot of stuff, but I'd be tickled to see it raining inside the garage.
Err - anyway - I'm not sure I'd like the idea of wind going directly into the mining rig enclosure, though.