Are there airbrushing temperature limits?

I would not use enamels at lower than 65 degrees.  They are more critical than acrylics because of the long dry time, but I would not even use acrylics much below 60.

I have let impatience get the better of me on occasion and taken a model outside in sub freezing temps and hit it with a coat of paint and it turned out fine.  I DID keep the paint and model inside until the last second and brought them back in as soon as the overspray settled and sat it in the bathroom with the exhaust fan on for a few hours 'til it dried.  -and no, the wife was not amused.

I wouldn't even store model paints out there if it's that cold.  Keep them inside until you're ready to paint.  Maybe place a heat lamp in a corner where you work to keep the temp up while you paint. A safe distance from the model of course. ; )

I will occasionally paint something in the garage with the door partially opened in cold temps (I live in SW Idaho) the temp in my garage in Winter usually hovers around 53 degrees F.  I will usually bring the model and paint right back in with me and take it upstairs where my modeling supplies are and close the door.  Like CN Spots, my wife isn't usually thrilled with this approach, but it is better than spraying inside the house.