February 2 is known as Groundhog Day in Punxsutawney, Pennsylvania. According to popular legend, an early spring is predicted if, on that day, the groundhog does what?

The popular legend of Groundhog Day is rooted in a simple, if unscientific, form of weather forecasting. The tradition holds that if the day is overcast and cloudy, the groundhog will not be able to see its shadow upon emerging from its burrow. This is taken as a sign that winter is losing its grip and an early spring is on its way. Conversely, a clear, sunny day means the groundhog will cast a shadow, which supposedly frightens it back into hibernation for six more weeks of cold weather.

This American tradition was brought to Pennsylvania by German immigrants in the 18th and 19th centuries. It stems from the European holiday of Candlemas, which also falls on February 2. An old German proverb stated that if a hedgehog or badger saw its shadow on Candlemas, winter would persist. Upon settling in Pennsylvania, where hedgehogs were not common, the immigrants adapted the custom to the local groundhog, a fellow hibernating animal.

Today, the ceremony in Punxsutawney, Pennsylvania, featuring a groundhog named Punxsutawney Phil, is the most famous of these events. While a beloved cultural tradition, its accuracy is highly questionable. According to data from the National Centers for Environmental Information, Phil's predictions have been correct less than half the time, making the folklore more about fun and chasing away the winter blues than reliable meteorology.