Wiarton Willie predicts an early spring, but should we trust him? Here's his hit rate over the last decade

Groundhog Day moves online From CTV Kitchener's Leighanne Evans: Wiarton Willie moved his predictions online this year and is calling for an early spring.

KITCHENER — Every year in early February, people across Canada turn to unlikely sources of hope: groundhogs.

On Feb. 2, Ontario's own Wiarton Willie emerges from his home to predict whether Canadians will see an early or late spring. His decision all depends on whether or not he sees his shadow.

This year, he called for an early spring, something that the rodent prognosticator has done seven times since 2011. The exceptions were in 2011, 2014, 2016 and 2018.

It's not always a united front from the weather woodchucks, though: this year, while Nova Scotia’s Shubenacadie Sam agrees with Willie’s prediction, Pennsylvania's Punxsutawney Phil disagreed with Willie, calling for six more weeks of winter.

The division begs the question: if we're going to put our faith in a groundhog, who can we trust? Here's how Wiarton's weather oracle has fared over the years.

WHAT MAKES FOR AN 'EARLY SPRING'?

First, let's set some ground rules for determining the famous groundhog's hit rate.

Using data from Environment Canada that stretches from 1981 to 2010, the average temperatures in degrees Celsius for Waterloo and Wellington were:

For the purposes of measuring his predictions, we'll consider years where the temperatures were above average in two of the three months as "early springs."

In close cases, consideration will be given to the context of the temperatures, as well.

WILLIE'S TRACK RECORD

With that in mind, here is a look at how Wiarton Willie has done since 2011. All temperatures noted are in degrees Celsius and were retrieved from Environment Canada.

2020:

Prediction: early spring

Average temps:

Verdict: Wrong. While March was warmer than usual, winter hung around a bit as April and May saw temperatures below average.

2019:

Prediction: early spring

Average temps:

Verdict: Wrong. We're not sure what was going on with Willie this year, but Willie missed the boat across the board. All three months were below average in 2019.

2018:

Prediction: late spring

Average temps:

Verdict: Correct. When he saw his shadow that day, Willie knew that we were in for a long winter. When spring finally came around, it arrived in full force.

2017:

Prediction: early spring

Average temps:

Verdict: Toss-up. While two of the three categories here were technically below zero, they were so close to seasonal—0.3 and 1.3 degrees Celsius respectively—that the two degrees above average for April makes this a push.

2016:

Prediction: late spring

Average temps:

Verdict: Wrong. A warm March lent itself to an early spring before a frosty April took over. We're sure that the woodchuck was wishing for a frosty May but alas, spring prevailed.

2015:

Prediction: early spring

Average temps:

Verdict: Toss-up. While Willie again whiffed on two categories, April's average of 6 C was just 0.2 degrees below average before a much warmer-than-usual May. That makes this another push.

2014:

Prediction: late spring

Average temps:

Verdict: Correct. A bitterly cold March that was more than five degrees colder than average led into a chillier-than-normal April. May barely exceeded its average temperature. Nice job, Willie.

2013:

Prediction: early spring

Average temps:

Verdict: Wrong. This was a near-average year in terms of weather. Each of our three sample months was within 1.2 degrees of its average since 1981.

2012:

Prediction: early spring

Average temps:

Verdict: Correct. The year 2012 was a good one for the famous groundhog. March was a whopping seven degrees warmer than usual, while May reached nearly two degrees above average. April dipped below average but just barely at 0.4 degrees below normal.

2011:

Prediction: late spring

Average temps:

Verdict: Correct. This is exactly the late spring that Willie called for. The temperatures compared to average slowly trended up, from below average in March to near average in April, ultimately bringing a warmer-than-average May.

OVERALL PERFORMANCE

In the past 10 years, Willie has had two predictions that were too close to call, making the other eight predictions an even split.

A hit rate of 50 per cent gives Wiarton Willie a passing grade, which, combined with how cute he is, has made him a trusted weather predictor in southern Ontario over the past decade.

STUDENTS FIND 32 PER CENT ACCURACY

Emily Swerdfager and Shalini Kathirgamanathan, who are taking environmental sciences at the University of Waterloo, also wanted to find out how accurate Willie's predictions are. They studied his prognostications over the past 22 years.

“As a whole on average what we found is that sadly Wiarton Willie is only 32 per cent accurate with his predictions, which is less than randomly guessing,” Kathirgamanathan said.

They collected daily temperature data from February and March for each of those 22 years, using those to find an average to compare to the actual temperatures.

"We saw for each of those years whether it was cooler or warmer than the baseline temperature and then compared it with Willie’s predictions," Kathirgamanathan said.

The pair wanted to relate it back to climate change.

“He’s actually getting better at predicting whether or not there will be an early spring," Swerdfager said. "What we’ve found is that could have to do with the fact that we’re also seeing warming temperatures in the region.”