All the fun centers around Punxsutawney Phil, who leaves his burrow today in search of his shadow.
Whether he sees it or not is said to determine how many more weeks until spring arrives.
Click here for frequently asked questions about Groundhog Day from the Punxsutawney Groundhog Club.
Click here for a look at Phil's past predictions.
Click here for some Groundhog Day history.
Click here for some Groundhog Day fun facts.