Groundhog .org. This is the Official Site of the Punxsutawney Groundhog Club. This is the most minor of holidays but it always gets attention from my students. This is a good place to refer them towards.
From the site:
Yes! Punxsutawney Phil is the only true weather forecasting groundhog. The others are just impostors.
There has only been one Punxsutawney Phil. He has been making predictions for over 119 years!
Punxsutawney Phil gets his longevity from drinking "groundhog punch," a secret recipe. Phil takes one sip every summer at the Groundhog Picnic and it magically gives him seven more years of life.
On February 2, Phil comes out of his burrow on Gobbler's Knob - in front of thousands of followers from all over the world - to predict the weather for the rest of winter.