Prague in the snow
If you should be arriving at Prague in December, prepare yourself to bundle up. The normal high is 2°C/36°F and normal low -2°C/28°F, that are conditions much like south inland Canada, Chicago or Detroit in the united states, and Zurich in Switzerland. The average precipitation in December is less than 25 mm (1 inches) and certainly will take the form of snow or light rainfall. Prague winter months can be quite crisp and you will be pleased to put-on gloves, a warm scarf and a hat. Layering your garments is useful. Make sure that your foot are kept cozy in sturdy cold temperatures shoes with a water resistant sole. Avoid high heel shoes if you're able to - this goes for anytime of the year in the event that you intend to do plenty of walking in Prague.
You need to get fortunate to have a white Christmas time in Prague. Snow often comes and melts before Christmas time or doesn't come anyway until January. There's a Czech stating that goes such as this: "St. Catherine on ice, Christmas on mud". St. Catherine's Day is on Nov. 25, if you trust the folklore wisdom, you can view just what the elements's like on that day and you will know very well what to expect at Christmas time.