How Accurate Is Woodstock Willie?

Looking back at 10 years of groundhog weather forecasts.

This year marks the 30th anniversary of the filming of Groundhog Day in Woodstock and is yet another chance for us to marvel at the weather-predicting abilities of Woodstock Willie. 

So, I’m asking the age-old question: How accurate is a groundhog at predicting the weather?

I’m formulating an answer to that question by using data for the past 10 years. For the analysis, I built on one Justin Ballard at WREX did in 2020. I used the daily and historic average temperatures for March 2020 and March 2021 from Wunderground.com for the Rockford International Airport Station (the closest weather station with historic data). I then calculated the overall average temperature. If the actual average temperature was higher than the historic average, I considered that an “early spring.”

Over the past 10 years, Woodstock Willie has correctly predicted the forecast 50% of the time—although only 25% of the time over the past five years.  

Overall, Woodstock Willie has predicted an early spring (by seeing no shadow) four times in the past 10 years.

Punxsutawney Phil, on the other hand, has only predicted an early spring 20 out of the 124 years for which records exist, according to the National Oceanic and Atmospheric Administration. Over the past 10 years, Phil has also been 50% accurate.