The celebration of Groundhog Day had its origins from ancient European weather
lore. The early American reference to the custom can be found in a diary entry,
dated February 4, 1841, made by a Berks County, Pennsylvania storekeeper
James Morris. It was celebrated for the first time at Gobbler’s Knob in  the
city of Punxsutawney, Pennsylvania. Traditionally, if a groundhog comes out 
of his hole and sees its shadow, that means there will be six more weeks of
winter weather, no shadow means an early spring.