Everyone complains about “the weather” and the “weather forecast”, but forecasting accuracy has improved markedly since 1980, which was already at least twice as accurate of the best (pre-computer) forecasts of the 1940’s and 1950’s.

Unfortunately, there is no really simple intuitive way to gauge the improving accuracy, but scientists have provided a variety of measures to indicate the relative improvement.

Improved Accuracy

36 hour and 72 hour forecast accuracy doubled in the 40 years between 1975 and 2015.

The same level of forecast accuracy was available 8 days out in 2010 as it was 5.5 days out in 1980.

The correlation between forecast and actual weather has improved consistently between 1981 and 2019 for 3-5-7-10 day forecasts. A 5-day forecast today is as accurate as a 1 day forecast in 1980. 9-10 day forecasts are useful today.

A seven-day forecast can accurately predict the weather about 80 percent of the time and a five-day forecast can accurately predict the weather approximately 90 percent of the time. However, a 10-day—or longer—forecast is only right about half the time.

https://scijinks.gov/forecast-reliability/

a five-day forecast is accurate about 80% (link resides outside ibm) of the time. A one-day temperature forecast is typically accurate within 2.5 degrees. 

https://www.ibm.com/weather/industries/broadcast-media/complete-guide-accurate-weather-forcasting

Short-term five-day forecasts are nearly as accurate as two-day projections were three decades ago. 

https://www.economist.com/the-economist-explains/2016/06/19/why-weather-forecasts-are-so-often-wrong?utm_medium=cpc.adword.pd&utm_source=google&ppccampaignID=17210591673&ppcadID=&utm_campaign=a.22brand_pmax&utm_content=conversion.direct-response.anonymous&gclid=CjwKCAjwvsqZBhAlEiwAqAHElZO7mctbaDFRsc83TSJlpoo-H_PIt1K9AGhjeyzGBxCppPXW_Fv6rBoCTbsQAvD_BwE&gclsrc=aw.ds

The forecast error rate has dropped by anywhere from about 70% (for a 24-hour forecast) to about 90% (for a 72-hour forecast) since 1970. To put that in perspective, the average error for a 72-hour forecast was about 450 miles off in 1970. Today, it’s about 50 miles off.

https://www.cnn.com/2022/06/25/health/weather-forecasting-future-scn/index.html#:~:text=The%20forecast%20error%20rate%20has,it%27s%20about%2050%20miles%20off.

History of Weather Forecasting

https://www.britannica.com/science/weather-forecasting/Long-range-forecasting

https://www.foxweather.com/earth-space/46-years-of-goes-how-a-history-of-achievements-has-changed-weather-forecasting

https://www.newyorker.com/magazine/2019/07/01/why-weather-forecasting-keeps-getting-better

https://celebrating200years.noaa.gov/foundations/numerical_wx_pred/welcome.html#intro

https://public.wmo.int/en/bulletin/weather-and-climate-forecasting-chronicle-revolution

Glorious Weather Forecasting Future

https://www.ibm.com/weather/industries/broadcast-media/complete-guide-accurate-weather-forcasting

https://www.nae.edu/244878/Future-of-Weather-Forecasting

https://celebrating200years.noaa.gov/foundations/numerical_wx_pred/welcome.html#ahead

https://www.wired.com/story/weather-forecasting-artifical-intelligence/

https://www.washington.edu/news/2020/12/15/a-i-model-shows-promise-to-generate-faster-more-accurate-weather-forecasts/