Who made the most skillful forecast?
Online providers like WeatherChannel (weather.com) or the National Weather Service? How does this answer vary across the United States? And how good is the forecast? perseverance–just predict today what happened yesterday?
Such questions will be considered in the blog.
In fact, there is an online website that provides answers to such questions: forecastadvisor.com (see sample below). They evaluated temperature and precipitation forecasts for hundreds of cities by looking at 1-3 day forecasts. They defined temperature accuracy as the percentage of forecasts within 3F of what was observed. Precipitation accuracy was the percentage of precipitation forecasts that were correct (rainfall vs. no rain).
Looking at the 2023 stats, the results show that the most skillful forecasts for each city come from the private sector (see table below), with weatherchannel/weather.com (WC) generally coming out on top, except for a few cities where Microsoft (MS) is the best. The National Weather Service isn’t the best anywhere.
I thought it would be interesting to plot the difference in percent accuracy between the top finisher and the National Weather Service (shown below) on a map. The higher the number, the further behind the National Weather Service is, with numbers ranging from 1.6 to 11.5 percent.
The National Weather Service’s Chicago office was the best…just 1.6% behind mine. On the other hand, the Boston, Houston, Cleveland, and San Francisco offices weren’t so good. Not so good in Seattle (8.7).
Why is the NWS Chicago office so good? Not that the weather is boring there! Obviously the local staff and leadership are great.
The chart above shows that the most accurate forecast locations include San Francisco (SFO) and Los Angeles (LAX). Not surprising, given the lack of storms and generally mild weather that prevails in coastal California. Oddly enough, Anchorage is a close second. Maybe it’s just boringly cold.
The lowest skill was in Chicago where there were storms, thunderstorms, cold fronts, and more. Kudos again to the NWS Chicago office!
Finally, there is persistent forecasting (again, predicting tomorrow to experience what happened today). Dreary LAX had some decent persistent forecasting (73% correct!), but stormy/volatile Chicago had a persistent forecasting skill of only 43%. Another kudos to the Chicago NWS office.
In short: If you like consistently dull weather and tricky forecasts, head to the California coast. If you like stormy/changeable weather, Chicago should be on your itinerary.
Want good weather forecasts? The National Weather Service’s forecast shouldn’t be your top priority.
