I’ve flown both my Spark and P3S at temps below -20C and fly just as much in the winter as I do in the other seasons. In cold temps as others have mentioned you can keep the
battery warm in pockets close to your body or use a
battery warmer. I use a Turnigy
battery warmer as well as my pockets when I am out Nordic skiing or snowmobiling. As far as
battery flight time in cold, I have not seen much difference.
I do find the Spark gimbal much more sensitive to cold weather than my larger drone. As the temp approaches 0C the gimbal becomes sticky - it doesn’t pitch down the full range or it gets stuck for a moment. Sometimes I will hover and do a few pitches up and down to free it up. The automated pano functions usually do not work in cold wearther. Surprisingly, I have not had a problem with roll and everything else works fine.
The biggest problem you will have is keeping warm, especially your fingers. Also it’s worth it to note that the touch screen on your flying device may become less sensitive or not work well and just like your flight
batteries you will need to keep it warm, but unlike the drone
batteries that warm up during flight, your devices
battery will not. I have had my iphone go dead on me but everything else works. Another reason why VLOS is so important especially in winter.
Hope this helps.
Chris