Some of my favorite drone videos are those taken in the winter with snow covered trees and frozen lakes. But the winter also brings a harsh environment that can be hard on all flying machines - drones included. Here's some tips for flying safe and taking great shots in the bitter cold.
Keep yourself warm
Before you worry about how to handle your drone, remember to keep yourself warm. It's very easy to underestimate the effects of the cold, especially when you are outside, standing still for 30 minutes or more. Besides the obvious of warm clothing, you should get a good pair of gloves that are appropriate for flying. This means they are thick enough to keep warm, but thin enough to comfortably work the sticks on the controller. I also highly recommend finding a pair with "touchscreen" fingers that are able to work with a screen. Otherwise, you'll find it very inconvenient to take off your gloves to use the screen.
Use ND filters
The snow brings an entirely different scene to the camera and you'll need to be prepared. Snow is excellent at reflecting light, which means very bright pictures. The camera will try to compensate for this by increasing the shutter speed and decreasing the ISO, but it's not uncommon for the camera to reach its limits and you will have photos that are overexposed (too bright). The best way to prevent this is to attach a Neutral Density Filter to your camera. An ND filter is like sunglasses for your camera, reducing the amount of light that enters the camera. They come in different strengths, depending on the conditions. You'll probably want an ND16 or higher for the white powder in daytime.
Keep the battery warm
This is probably the most important factor in cold weather flying. Batteries were designed to operate at about room temperature and have somewhat unpredictable behavior at colder temperatures. Colder temperatures result in lower voltages, meaning you can expect (at a minimum) shorter run times and in extreme cases - battery failure. The best thing you can do is keep the battery as warm as possible before the flight. That means keeping spare batteries indoors or in a warm vehicle. If you must travel with the spare batteries, keep them close to your body heat (inside a coat pocket for example). Once you are ready to fly, take off slowly and monitor any warnings closely. This way, if the battery really is too cold and the system shuts off, it doesn't fall very far.
Gentle on the sticks
For a variety of reasons, you'll want to fly your drone a bit slower and more gentle in the winter. From the point above on battery voltage in the cold, high acceleration uses a lot of power and can stress a battery that is already struggling. The colder air also can affect flight dynamics and the drone may not respond in they way you are used to flying. For example, cold air is denser, which means the props are slightly more effective and response/speed will increases more than you are used to in the warmer air. Take some time to learn how to fly in the cold before you attempt any aggressive flying.
The winter typically brings a lot of water in various forms. Along with rain, you can expect heavy fog, snow, and condensation - all of which are not friendly to electronic devices such as drones. Get in the habit of monitoring the weather much more closely before and during your flight. If you suspect that rain or snow is imminent, land your drone ASAP. Try to avoid flying in heavy fog and high humidity. Besides the moisture, it is easy to loose sight of your drone even at close distances.
Use a landing pad
If you are flying in a snow-covered area, you'll need to be extra careful about where you land. The snow may not be able to support the weight of your drone, especially if the snow is fresh. Landing could result in your drone sinking into a pile of snow. You'll then be trying to unbury sensitive electronics that are probably warm enough to melt the snow around it. Make sure you have a designated dry area for takeoff and landing, and that you are always within easy reach if you have to land quickly. If you have to takeoff from snow, at the very least pack it down tightly. Also keep in mind that the propellers can give off quite a gust of air, throwing nearby snow around.