El Niño and the Groundhog – Science and Folklore

October 13, 2016
Groundhog's Day

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Groundhog Day is coming! Will the groundhog see his shadow? If we were in the middle of an El Niño, he might just see it. Behind the rodent folklore is an odd bit of science trivia.

The Folklore—Look at the legend that has had folks trekking to Punxsutawney, Pennsylvania since 1887. According to the folklore, if Phil the groundhog comes out of his hole and sees his shadow on February 2, it means there will be six more weeks of really crummy weather. If not, the rest of winter will melt away.


This legend is a holdover from European folklore. Since medieval times, people watched hedgehogs, badgers, bears or wolves to see if they saw their shadows on Candlemas, February 2. Once people settled in America, the local groundhogs took the place of bears, badgers and other critters.

According to the National Climate Data Center (NCDC), the tradition became publicized in 1887 when a newspaperman wrote about local hunters who celebrated February 2 by going on a groundhog hunt, followed by a jolly groundhog barbecue. He embellished the story with tales of the forecasting skills of Punxsutawney Phil. The rest is history.

The Science—When people continue a weather tradition, it is usually because it contains at least a small grain of truth. Historically the grain of truth for Groundhog’s Day in America is related to the El Niño.

The El Niño, an abnormally warm Tropical Pacific current, warps global wind and weather patterns. In North America it usually produces a warm winter starting along the West Coast and expanding eastward. By mid-winter, the warmth of a moderate to large El Niño usually reaches the Great Lakes and Midwest. Then, as the El Niño weakens, the warmth retreats and normal winter returns to the East.



In large parts of the East, this means an El Niño frequently produces a cool early winter, warm mid-winter and cool late winter. If a large rodent was wandering around in the relatively mild mid-winter, there might be enough sunshine to see his shadow. Then the El Niño would weaken and winter would literally come storming back.

It should be remembered that the Groundhog tradition persisted in America during the 1700s and 1800s, during the last stages of the “Little Ice Age.” What occasionally worked during those chilly times may not work now. The NCDC claims that since 1988, groundhogs have only had a 39% accuracy rate.

Accurate or not—it’s a great holiday and a good excuse for a party or barbecue.

Is the weather mild enough that a groundhog would see his shadow in your area? Do you think the rest of winter will be harsh or will it finally ease up?

About This Blog

Are you a weather watcher? Welcome to “Weather Whispers” by James Garriss and until recently, Evelyn Browning Garriss. With expertise and humor, this column covers everything weather—from weather forecasts to WHY extreme weather happens to ways that weather affects your life from farming to your grocery bill. Enjoy weather facts, folklore, and fun!

With heavy hearts, we share the news that historical climatologist and immensely entertaining Almanac contributor Evelyn Browning Garriss passed away in late June 2017. Evelyn shared her lifetime of weather knowledge with Almanac editors and readers, explaining weather phenomena in conversation and expounding on topics in articles for the print edition of The Old Farmer’s Almanac as well as in these articles. We were honored to know and work with her as her time allowed, which is to say when she was not giving lectures to, writing articles for, and consulting with scientists, academia, investors, and government agencies around the world. She will be greatly missed by the Almanac staff and readers.

Reader Comments

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el nino

I think we are going to see a replay of the winter of 1996 on the east coast. Large snow storms followed by rain storms in between making it seem like winter is over until the next snow storm hits

Nino, Nina, Shmina!

Hey guys! We are talking about El Nino because the mid-winter thaw happens around Feb. 2 during El Nino years...SOOOooOOooo, it will PROBABLY not work here, in a La Nina (sort of) winter! HISTORICALLY, we se the groundhog's accuracy based on a short warming trend at this time, ESPECIALLY during the mini Ice Age....
If you want perfect predictions, wait until next year, look into the records and predict 2011's weather in 2012 using 20/20 hindsight.
OR....you can get into the fun of it and cheer on your own particular favorite greasy vermin infested rodent! After which I suggest we all get back to the BBR and know back a few brewskies, tell lies about the weather when WE were kids & envy Bill Murray for being stuck with Andy McDowell for 1,000 Groundhog Days.

General Lee

In Georgia, we rely on General Beauregard Lee at the Yellow River Game Ranch for our Groundhog Day prediction.

but we are in a La Nina weather pattern.

not sure why you are banging on about El Nina when we are in the middle of a La Nina weather pattern...


More importantly, Candlemas is an old cross quarter day, halfway between the winter solstice and the vernal equinox. Whether we like it or not, there are in fact six weeks left of winter.

El Nino?

This is a la nina winter im not sure why this article is talking about el nino.

El Nino

I was talking about El Nino because that is when the Groundhog shadow trick works in the Eastern US. As we will see tomorrow, when you have a La Nina winter, it's usually overcast and snowy on Groundhog's Day.

but its la nina

cool story.

A Southern Groundhog

I just had a reader remind me of the talented Chattanooga Chuck, in case you want to visit a more southern celebration.
Can readers recommend any other Groundhog Day festivals?

Who knew?!

 I knew the Groundhog Day lore was from Germany but had no idea of the connection with the El Nino and what's happening with the weather forecasts. Very interesting.


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