Punxsutawney Phil Groundhog Day Web site, Groundhog Day is the result of a blend of ancient Christian and Roman customs that came together in Germany.
Tradition held that the weather on Candlemas was important: clear skies meant an extended winter.
Legend has it that the Romans also believed that conditions during the first days of February were good predictors of future weather, but the empire looked to hedgehogs for their forecasts.
These two traditions melded in Germany, and was brought over to the United States by German immigrants who settled in Pennsylvania. Lacking hedgehogs, the German settlers substituted native groundhogs in the ritual, and Groundhog Day was born.” More: