Groundhog Day is celebrated in the U.S. each year on February 2nd. On this day in mid-winter, the groundhog awakens from a long winter's nap, and goes outside of his den to see if he sees his shadow. This tradition is big on an otherwise cold and dreary mid-winter's day.
According to legend, if the groundhog sees his shadow (a sunny morning), there will be six more weeks of winter. He then returns to his den and goes back to sleep. If however, he does not see his shadow (cloudy days), he plays around outside of his hole for a while. If he does not see his shadow, spring is just around the corner.
The Groundhog's Day tradition travelled long ways. It comes from German roots. German immigrants brought the tradition with them from Germany. As they settled in hills of Pennsylvania, they began the tradition of using the Groundhog to predict the the arrival of Spring. The tradition is based upon Candlemas, the day that is the midpoint between Winter and Spring.
A famous Candlemas Poems Goes:
If Candlemas be fair and bright,
Winter has another flight.
If Candlemas brings clouds and rain,
Winter will not come again.