Had the opportunity to fly in Harbin, China in a -26 to -31 degree environment. I had the gimbal frozen once during flight and have to fly back to free it. It could be due to some moisture(melted snow) that gets into the gimbal and freeze up instantly when I took it out of the bag.
The Mavic Pro handles the cold well (no noticeable reduction in flight time) , but not my hand and phone. My iPhone 7 plus shuts down after about 10min with 100% charge. Have to auto RTH once as I lose FPV connection. My fingers becomes numb and later extreme pain, risking frost bite.
Anyway, all is well and my fingers are intact and Mavic Pro is safe.
Enjoy the flight.