If Phil, the groundhog, emerges from his hole and sees his shadow, there will be six more weeks of cold weather.
As of 2017 Punxsutawney Phil had made 131 predictions - only 18 times going for the "no shadow" early spring.
In reality, Phil's prediction is decided ahead of time by the group on Gobbler's Knob, a tiny hill just outside Punxsutawney about 65 miles northeast of Pittsburgh.
The standing Punxsutawney Groundhog Club president is the only person able to interpret Phil's official language known as "Groundhogese". Toby Ault, a Cornell assistant professor of earth and atmospheric sciences, says the tool is based on weather data linked with leaf-out and bloom in cloned lilacs and honeysuckle. It was the first time the weather guru rodent was celebrated at Gobbler's Knob in Punxsutawney, Pennsylvania. Would winter last six more weeks, or would there be a reprieve?
Over the years Pennsylvania's Punxsutawney Phil, whose full name is "Punxsutawney Phil, Seer of Seers, Sage of Sages, Prognosticator of Prognosticators, and Weather Prophet Extraordinary", has grown into a household name. Here's how to live stream the annual ceremony to find out if we'll have an extended winter or early spring!
But a cautionary word: It's not just Phil. Over the last 30 years, Phil has only been right 20% of the time - must be all that wild grass he's eating. Not lead, but solid gold: I see my royal Shadow!
However, Groundhog Day became a tradition over 130 years ago - dating back to 1880s.
Punxitawney Phil's accuracy rate is around 39 percent.
Members of the Groundhog Club's "inner circle" say Phil's long life can be attributed to drinking a secret punch every summer at the Groundhog Picnic. The German settlers switched to groundhogs when the settlers noticed a surplus of the creatures in Pennsylvania.
Groundhog Day originated from the Christian celebration Candlemas Day, which marked the midpoint between the winter solstice and the spring equinox.
Thousands of visitors come to Punxsutawney to see Phil every Groundhog DayWhen is Groundhog Day 2018 and what are its origins? Because of this, Phil spends the year at his house located inside the Punxsutawney Memorial Library.