How accurate are groundhog Phil, Farmers’ Almanac compared to traditional forecasts?
After “Punxsutawney Phil” predicted six more weeks of this year’s winter, southwest Illinois and St. Louis area residents may be wondering if the groundhog’s prediction will hold up or if they should rely on more traditional weather forecasts.
Traditional weather forecast organizations, such as the National Weather Service, AccuWeather and many others, base their predictions in meteorology. Others are more creative and mysterious, such as the Farmers’ Almanac.
But no organization can predict the weather with 100% accuracy all the time, so how much of a difference does it make? Here’s what to know.
Traditional weather forecasting
A seven-day forecast can accurately predict the weather about 80% of the time, and a five-day forecast has a 90% accuracy rate, the National Oceanic and Atmospheric Administration reports.
Accuracy levels decline as the forecast length increases, though. A 10-day or longer forecast is only right about half the time, NOAA says.
“Meteorologists use computer programs called weather models to make forecasts. Since we can’t collect data from the future, models have to use estimates and assumptions to predict future weather, the NOAA website reads. “The atmosphere is changing all the time, so those estimates are less reliable the further you get into the future.”
Groundhog Phil’s accuracy
NOAA reports groundhog Phil’s weather forecast accuracy is 40% for the U.S. as a whole.
Phil predicted Feb. 2 the country would see six more weeks of winter before spring makes its debut. But the St. Louis region has seen above average temperatures recently, with forecast highs reaching 60 and 66 degrees Fahrenheit Monday and Wednesday.
A typical February in the St. Louis area would have lows of 27.6 degrees and high temperatures of 45.8 degrees, the NWS St. Louis office reported, using data from 1991 to 2020.
Farmers’ Almanac accuracy
The Farmers’ Almanac claims its forecasts are “amazingly accurate,” correctly predicting the weather about 80% to 85% of the time. But a 2010 University of Illinois study found the almanac was only right about 52% of the time, Popular Mechanics reported.
The almanac predicts Illinois will have a cool, very stormy spring, while Missouri and surrounding states will see “coolish” temperatures and above normal precipitation.
The almanac makes predictions based on a mysterious formula that considers factors such as planetary positioning, sunspot activity and tidal action of the moon.
“The only person who knows the exact formula is the Farmers’ Almanac weather prognosticator who goes by the pseudonym of Caleb Weatherbee,” the organization’s website says. “To protect this proprietary formula, the editors of the Farmers’ Almanac prefer to keep both Caleb’s true identity and the formula a closely guarded brand secret.”
Editors “firmly deny” using any type of computer satellite tracking equipment, weather lore or groundhogs. They say they use a specific and reliable set of rules developed in 1818 by the almanac’s first editor, an astronomer and mathematician named David Young. The rules have been altered slightly and turned into an astronomical, mathematical formula, the almanac says.
As the Farmers’ Almanac’s prediction formula is secret, it’s difficult to compare to more popular meteorological practices, but many scientists dispute the Almanac’s accuracy.
