Hi, I have the same question and can't find the direct answer. So I have checked datasheets of some core components and their low operating temperatures are -40°C.
However there are lot of other components that I didn't check and some of them may not operate at such a low temperature.
So in general I would recommend to not operate at temperature lower than 0°C (which is guaranteed by all the modern RC components).
How do the Lipos do at those temps?
Joshua - did you ever get an answer to your question regarding the Pixhawk components operating in the cold?
They do pretty bad. The one I use (Turnigy 4S 5A 30C) drop 1.5 V even at +5°C.
The general recommendation for LiPo operating temperatures are:
charge: 0°C - 45°C
discharge: 0°C - 60°C
Here is a good explanation on the LiPo operating temperatures: http://batteryuniversity.com/learn/article/discharging_at_high_and_...
Here is another guide on the LiPo batteries: http://www.rctoys.com/pdf/THPSafetyWarnings.pdf
I am in Canada. Currently the temperature is about -10˚C. It works well. The battery itself can produce heat during flight. A high discharge rate battery is recommend to lower the voltage drop. Also you can wrap the battery with some warm clothes.
From our experience -10 °C is absolute minimum for all Pixhawk varietes what we had in hands. The same for ESCs from different manufacturers. And for DJI avionics too.
You can use you drones below -10, but you should do all preparations in your car/house and don't left your drone outside longer then couple of minutes.
I've flown hexa Pixhawk that was overnight in car at -15..20 , worked just fine, both that, and 3DR radios and video tx.
From formal point of view Pixhawk (at least old one manufactured by 3DR in past) uses components rated for industrial range from -40°C.
It seems that root of problems is in thermal calibration of sensors. Sensors should be calibrated for whole range of working temperatures and I suppose that they calibrated for "normal" temperatures only.
This stuff is outside of my knowledge but I saw lot of problems with our fleet (>50 drones of different makes) in low temperatures.
Our chief electronics engineer just told me that each autopilot should be calibrated individually. This requires a thermal chamber. I'm sure that manufacturers of inexpensive autopilots do not do this.
We found that only orignal 3dr pixhawks dont have problems with below 0 temperatures. We tested it even under -20'C. Chinese pixhawk copies often doednt want to pass initialization below 0.
its good idea to carry batteries in pants pockets ;) before flight during winter flights.