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CLEVELAND, Ohio — The Old Farmer’s Almanac says its long-range forecasts are traditionally about 80% accurate. An independent study of five years of forecasts found that about 51% of its monthly temperature and precipitation predictions were correct, a result described as similar to chance.
The accuracy question arises as the publication releases its new fall forecast for Northeast Ohio. The outlook calls for a cooler-than-normal September, near-normal October temperatures and generally normal to slightly below-normal rainfall.
A review of the almanac’s methods, independent assessments and recent Cleveland results shows a mixed record. Its broad forecast for Cleveland last fall was directionally correct, but its specific October predictions were not.
What the 80% claim measures
The Old Farmer’s Almanac says its proprietary forecasting formula combines solar science, climatology and meteorology. It defines solar science as the study of sunspots and other solar activity and says it compares current solar patterns with historical weather conditions.
The formula traces its origins to one devised by founder Robert B. Thomas in 1792. The almanac does not publicly disclose the formula, although it says its technology and methods are continually updated.
In a self-evaluation published Nov. 7, 2025, the almanac gave its winter 2024-25 forecast an overall accuracy score of 86.1%. It reported correctly forecasting the direction of temperature departures in 88.9% of its regions and precipitation departures in 83.3%.
Those percentages do not mean it predicted exact temperatures, precipitation totals or storm timing in more than 8 of every 10 cases. The evaluation measured whether conditions in one representative city in each region finished above or below normal. The almanac conducted the evaluation itself.
Northeast Ohio is part of the Lower Lakes region, which covers portions of several states. A correct regional trend therefore does not establish that the forecast matched conditions in every community.
Independent study found results near chance
A 1981 study published in Weatherwise by University of Illinois atmospheric researchers John E. Walsh and David Allen examined five years of almanac forecasts.
The researchers compared the almanac’s monthly temperature and precipitation predictions with recorded weather data. They found 50.7% of the temperature forecasts and 51.9% of the precipitation forecasts were correct.
According to a University of Illinois Extension summary of the study, those rates were similar to the 50% success rate expected by chance when choosing between two outcomes, such as above or below normal.
The study is more than four decades old. The almanac says it has refined its formula with newer technology and calculations, so the findings do not establish how its current system performs.
No recent, comprehensive evaluation of the current system by independent researchers was identified in the sources reviewed for this story.
A 2012 North Carolina State Climate Office review examined three winters of forecasts from The Old Farmer’s Almanac and the similarly named but separate Farmers’ Almanac.
The review did not produce an overall accuracy percentage. It found correct calls and misses from both publications. The Old Farmer’s Almanac captured the overall temperature trend in winter 2010-11 but underestimated the early-season cold. Its predictions for a wet December and cool February also did not occur during the warm, dry winter of 2011-12.
How it performed in Cleveland last fall
The almanac’s 2025 Lower Lakes outlook described September and October as cooler and drier than normal overall.
A published summary of the forecast projected 2.5 inches of September precipitation, 0.5 inches below normal, and 2 inches in October, 1 inch below normal. It also projected an October average temperature of 51 degrees, 2 degrees below normal for the region.
September largely matched the broader forecast. Cleveland Hopkins International Airport recorded an average temperature of 65.4 degrees, 1 degree below normal, according to the National Weather Service’s September 2025 climate report.
The airport received 0.75 inches of precipitation, 3.18 inches below Cleveland’s September normal.
October went in the opposite direction from the specific forecast. Cleveland averaged 55.5 degrees, 0.4 degrees above normal. Precipitation totaled 3.87 inches, 0.27 inches above normal, according to the National Weather Service’s October report.
Combined, September and October averaged about 0.3 degrees cooler than normal in Cleveland. The two months combined produced 4.62 inches of precipitation, 2.91 inches below the combined normal total.
The almanac therefore identified the broad two-month trend — cooler and drier — although its specific October temperature and precipitation predictions missed.
The comparison is a local spot check, not a comprehensive evaluation. It measures one weather station against a forecast written for a multistate region.
The National Oceanic and Atmospheric Administration’s Climate Prediction Center uses a different system. Its seasonal outlooks assign probabilities to above-, near- and below-normal conditions. Its public verification system compares forecasts with observed results and measures performance beyond the number of correct predictions expected by chance.
Because the almanac reports a self-calculated percentage based on representative cities and NOAA uses probability-based skill scores, the two organizations’ accuracy measurements are not directly comparable.
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