Although groundhogs may not be the best weather predictors, they do in fact emerge from dens in early February. This is the practice of males as they rouse themselves to wander around their 2- to 3-acre territories in search of burrows belonging to females, which the males will enter and where they may spend the night. Research suggests that no mating takes place at this time; the visits probably just let the animals get to know one another so that they can get right down to the business of breeding when they emerge for good in March. Outside of the mating season, woodchucks are solitary, except for females with young, which usually are born in early April.
The first official Groundhog Day celebration took place on February 2, 1887, in Punxsutawney, Pennsylvania. It was the brainchild of local newspaper editor Clymer Freas, who sold a group of businessmen and groundhog hunters—known collectively as the Punxsutawney Groundhog Club—on the idea. If it's sunny out, and he sees it, we're in for six more weeks of winter. On the other hand, a cloudy Groundhog Day is supposed to mean an early spring. Groundhog Day is really an astronomical holiday.
Known as an "edge" species, groundhogs prefer transitional areas where forest or woodland meets a well-vegetated open field or meadow. Groundhogs spend most of their time underground in complex burrow systems, which they dig in dry, well-drained soil. Most of the time groundhogs dig their burrows in areas with nearby cover such as fencerows, hedgerows, beside structures, home foundations or trees.