The best time for pruning varies with the type of tree but it is generally accepted that early winter is a good time to prune deciduous trees, as long as it is not frozen! If there is no freezing yet, the leaves are gone and you can easily inspect the branches and tree structure for any signs of weakness.
For Evergreen trees and shrubs, you should wait until after the last winter freeze before pruning. Early Spring is best.
After a heavy snow, your trees and bushes might be icy and covered with snow. It is best to wait until everything thaws before trying to assess damage. Shaking snow or ice off a plant can cause even more damage to it.
