Battery

I started my car today and it started fine like always but the after a few seconds the battery light came on for a second. Why would it be doing that?
Oh, It's cold up here. I live in Michigan.

The light could be caused by a slipping belt or a loose wire. I would check the belt first since you say it is cold, it could be dried out and slipping a little. Also make sure the belt tensioner is in good shape it could be you slippage problem.