Groundhog Day or Groundhog's Day is a holiday celebrated in New York and Pennsylvania on February 2. In weather lore, if a groundhog, also known as a woodchuck, marmot or ground squirrel, emerges from its burrow on this day and fails to see its shadow because the weather is cloudy, winter will soon end. If the groundhog sees its shadow, it will return into its burrow, and the winter will continue for 6 more weeks.

The groundhog (Marmota monax) is a rodent of the family Sciuridae, belonging to the group of large ground squirrels.