Try to make the best of it. Find things to do that you enjoy that are mostly for indoors. Build a puzzle, read a book, listen to music. Workout to a exercise DVD. Watch a funny movie. Sit by the window and let the sunshine hit your skin.
If you try to you will find that there are many ways to help you deal with the season change that make you feel upbeat and better about it.
At my website I have done an article specifically about this. It is very serious for some people as they can sink into terrible depression. It is a condition known as SAD or Seasonal Affective Disorder. Make sure not to take this lightly as it can develop into full blown depression if you let it get the better of you.