Editor's Note: (A version of this story was originally published on CNN.com in 2015.)
(CNN) The story goes that, in 1815, Old Farmer's Almanac founding editor Robert B. Thomas was interrupted by a boy wondering what to put down for the weather forecast of July 13, 1816.
In some versions, Thomas is ill with the flu. In others, he's simply preoccupied with other work. Whatever the reason, the entry for that day -- perhaps Thomas' suggestion, perhaps one from an impish interloper -- was supposedly "rain, sleet and snow." In July.
It so happened that 1816 was "the year without a summer," thanks to the eruption of Mount Tambora, and it did, indeed, sleet and snow that season, even in July. The forecast is alleged to have made the almanac's reputation.
Nevertheless, the almanac has become a closely watched predictor of weather, particularly winter weather. It recently released its forecast for 2016-17: It "forewarns that exceptionally cold, if not downright frigid weather will predominate over parts of the Northern Plains, Great Lakes, Midwest, Ohio Valley, the Middle Atlantic, Northeast, and New England this winter."
The forecast immediately started trending, as it seems to do every year. But does it have any validity?
Dave Hennen, senior meteorologist and executive producer for CNN Weather, says it should be taken with a grain of salt -- and not necessarily road salt.
"It's difficult enough to do a five-day forecast," he said. "We're really good at the day of and the next day, (and) we're better at temperature a ways out than precipitation. But to forecast out that far in advance ... even the science behind our long-range forecasting is sometimes not that solid."
The 225-year-old almanac, with its kitschy cover and homespun advice, noted in 2015 that it's "useful, with a pleasant degree of humor." The heart of the book, said editor Janice Stillman, is its calendar of the heavens, complete with various astronomical tables.
"From that springs all the rest of the content," she said from the almanac's offices in Dublin, New Hampshire, in 2015.
And the weather? According to its website, the almanac bases its forecasts on a "secret formula" (yes, just like Coca-Cola) that is "locked in a black box."
The formula itself has dollops of science to go along with its historical methods.
"Over the years, we have refined and enhanced that formula with state-of-the-art technology and modern scientific calculations," the site says. "We employ three scientific disciplines to make our long-range predictions: solar science, the study of sunspots and other solar activity; climatology, the study of prevailing weather patterns; and meteorology, the study of the atmosphere."
In press materials, the almanac claimed 96.3% accuracy for its "2015 predictions of a bleak and biting winter." Stillman says the figure is based on an analysis of the almanac's forecasts of its 16 regions on a monthly basis.
Meteorologists and weather experts don't buy it.
"Both (the Old Farmer's Almanac and its competition, the Farmers' Almanac) claim high accuracy rates (around 80 percent) but have never published evidence backing them up. They lack transparency and keep their methods 'closely guarded,' " wrote the Washington Post's Jason Samenow in 2013.
Added Dennis Mersereau of Gawker's "The Vane," "The Old Farmer's Almanac is to meteorology what astrology is to astronomy."
Stillman stands by the almanac's forecast.
"We are not really expecting that to happen," she says.
Even if it is wrong, people may not remember the specifics. Hennen points out that the Maine-based Farmers' Almanac -- the Old Farmer's Almanac's rival -- missed the forecast for the New Jersey-based Super Bowl in 2014, predicting a messy "Storm Bowl." The actual weather? Close to 50 degrees at kickoff.
(The Old Farmer's Almanac, which also predicted rough weather that day, noted in a comment response on its website that it was "on trend.")
After all, more than two centuries into its run, there's still a solid demand for the Old Farmer's Almanac. Stillman says that about 3 million copies are printed, and the title has 1.3 million fans on Facebook. Whether for entertainment or information, people read it for everything from gardening tips to holiday lists. (And, yes, weather forecasts.)
"It's a symbol and manifestation and perpetuation of country values in life," Stillman said.
Even Hennen is more amused than offended by the attention it brings. He tips his hat -- or should that be a nice wool toque? -- to the almanac's longevity, if not its methodology.
"(Long) before meteorologists were putting out their winter predictions, the (Old) Farmer's Almanac has been doing this," he said. "I think people remember that. Nowadays, even meteorologists are putting out outlooks for 'is it going to be a busy hurricane season?' 'Is it going to be a bad winter?' I think we're just kind of new to the game, whereas the (Old) Farmer's Almanac has been doing it forever."