How accurate are weather forecasts?
In general, weather forecasts are getting better, due to improvements in computer models, observations and our understanding of atmospheric. Accuracy depends on the purpose of the forecast and how far out it extends. Next-day forecasts of maximum temperature are good to within 3 or 4 degrees; however, the same forecast for a week from now are pretty bad.
The National Weather Service takes verification of its weather forecasts seriously and has procedures for verifying forecasts, as part of its effort to improve forecasting in general. For the public, accuracy may be less important than how useful a prediction is. If a forecaster predicts a 40 percent chance of precipitation tomorrow and it rains, was the forecast wrong? The answer will likely depend on what you planned to do tomorrow.
Forecast of hurricane movements have improved to the point that they can be used to anticipate landfall several days in advance. Six years ago the National Hurricane center didn’t issue four-day forecasts of hurricane tracks, but they now issue landfall forecasts along with their degree of uncertainty. Forecasts of hurricane intensity, however, have improved little since 2000.