Also in the winter, any water in your fuel and fuel line has the potential to freeze. With less fuel and more water, the chance of this occurring is greater. Also, as everyone knows, oil and water don't mix. The water could be separted from the fuel, and the chance of fuel line freeze-ups even greater. Keep another driving kit in the trunk.
Flares are easier to see in all conditions, expecially in snowy or foggy conditions.
However, there is some danger with flares. Check the flares at least once a month to be sure that there is no leakage from them. In addition, the flares are hot enough to burn metal and you could be severely burnt by the flares. Heed all safety warnings provided with the flares. Before leaving to go anywhere, clear all ice and snow off of all glass, front, back and sides, off of the mirrors, the headlights and taillights and off of your license plates.