September results in for ongoing 38-year study showing AccuWeather's unparalleled record of Proven Superior Accuracy™.
Washington, D.C. was the site for the study, which compares the accuracy of the AccuWeather and National Weather Service (NWS) forecasts, and dates back to January 1, 1988
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Each year, in the fall, the Yoshino cherry tree leaves turn a crimson red. Also in the image is the Washington Monument
The results are in for September of 2025 in the ongoing 38-year study comparing the accuracy of the AccuWeather and National Weather Service (NWS) forecasts, and AccuWeather continues its unparalleled record of proven Superior Accuracy™.
This study is by far the longest continuous verifications comparing the accuracy of AccuWeather and National Weather Service (NWS) forecasts; we have been comparing forecast accuracy for every day since January 1, 1988. Since 1998, the AccuWeather and NWS forecasts have also been compared to the automated forecast output created by the computer models run by the NWS, which has long been a basis for the NWS's forecasts.
The study compares the high and low-temperature forecasts for the upcoming day and night. Temperature was selected because the accuracy of temperature forecasts are measured by the NWS and can be compared in an objective, unbiased, and scientific fashion. Comparing the forecast and actual temperatures is straightforward in that it is simply the difference between the forecast temperatures and the actual temperatures reported by the NWS.
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The U.S. Supreme Court Court building behind autumn leaves in Washington, D.C., U.S. Photographer: Stefani Reynolds/Bloomberg
The site chosen for this study was Washington, DC, a forecast site that gives the NWS every advantage in this comparison. Since the NWS is headquartered, has its top management, and receives its oversight in the DC area, this should be the place where the NWS produces its best forecasts:
With that background in mind, here are the key points from the verifications for September 2025:
• In September, AccuWeather had a 0.75-degree F average error in Washington, DC while the National Weather Service (NWS) had an average error of 0.97 F and the automated computer forecast 1.37 F. This means that the AccuWeather forecast was 29.3% more accurate than the NWS and 82.7% more accurate than the automated forecast output. In September, AccuWeather’s average error of 0.75 was our lowest in two years, since our 0.70 error in September 2023.
• The AccuWeather forecast. has been more accurate than the NWS in more than 95% of the individual months since the study began in 1988 and AccuWeather has been more accurate in each and every one of the past 159 months since July 2012, which is more than 13 years of continual Superior Accuracy.
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Each year, in the fall, the Yoshino cherry tree leaves turn a crimson red. Also in the image is the Washington Monument
• AccuWeather has been more accurate than the automated computer forecasts in each and every one of the past 56 months. In contrast, the automated computer forecasts have been more accurate than those of the NWS in 6 of the past 13 months. This is especially significant because both AccuWeather and the NWS forecasts add the input of their meteorologists to the fully automated forecasts in their attempt to improve upon them. This demonstrates the additional value AccuWeather provides to the automated forecasts, which are generally used by AccuWeather competitors.
• Over the entire study period, AccuWeather forecasts have been 16.1% more accurate than those of the NWS. In the past nine months, AccuWeather had been more accurate by a very significant 36.4%.
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Over the entire study, AccuWeather forecasts have been 18.9% more accurate than the automated forecast outputs, while NWS forecasts have been 1.6% more accurate. This means that AccuWeather improved its forecasts over automated forecast output a dozen times as much as did the NWS.
A woman carries an umbrella while walking in the rain in San Francisco, Tuesday, Nov. 26, 2019. Northern California and southern Oregon residents are bracing for a 'bomb cyclone' that's expected at one of the busiest travel times of the year. (AP Photo/Jeff Chiu)
• Over the past year, AccuWeather forecasts have been 31.8% more accurate than the NWS forecasts and 31.6% more accurate than the automated forecast output.
• Over the past year, AccuWeather forecasts have been 36.5% more accurate than the automated forecast outputs, while NWS forecasts have been 2.6% more accurate. This means that AccuWeather improved its forecasts over automated forecast output fourteen times as much as did the NWS.
• The average margin of accuracy between the AccuWeather forecasts and what actually happened has been 1.204 degrees F over the past five years, which is nearly the smallest difference between the forecast and actual temperatures in any five-year period of the study, a smaller margin that any 5-year period before this year. Thus, AccuWeather forecasts continue to increase in accuracy.
• AccuWeather forecasts have been 18.1% more accurate than those of the NWS since the study began in 1988, 21.2% more accurate over the past five years, and 33.0% more accurate over the past year. Thus, AccuWeather’s edge in Superior Accuracy is continually increasing.
>>Better protect your employees and assets this winter with AccuWeather's Snow Warning ServiceTM. Contact AccuWeather today.
