Frequently Asked Questions

How did ForecastAdvisor get started?

ForecastAdvisor is a product for everyone who is interested in the what the weather will be. It answers not only the question "What will the weather be?" by providing the National Weather Service Digital Forecast Database forecast, but also "Who provides the most accurate weather forecast for my city?". It does this in a clean, easy-to-read format not cluttered with graphics and ads. ForecastAdvisor was created by ForecastWatch.

What does ForecastWatch do?

ForecastWatch calculates the accuracy, skill, and quality of weather forecasts. We collect over 40,000 forecasts each day from Accuweather, the National Weather Service, MyForecast,, and others for over 800 U.S. cities and 20 Canadian cities and compare them with what actually happened. With this information, we help weather forecast companies, businesses, and individuals:
  • Evaluate weather forecast providers
  • Improve decision-making where weather forecasts are used as input
  • Improve weather forecasts by providing useful feedback
  • Improve the quality of weather forecast websites
  • Provide additional data for decision and risk analysis
Weather plays an important role in our economy. Hundreds of thousands of businesses and individuals use weather forecasts every day to make decisions that have real economic impact. Hundreds of thousands more businesses and individuals could use weather forecasts as part of their daily planning process if the weather impacts on their businesses or the risks of using weather forecasts could be quantified. But until ForecastWatch, nobody had real data on who is the most accurate and skillful.

Why are the low temperature accuracy percentages generally lower than the high temperature percentages?

There are many reasons for this. One reason is that because ForecastWatch collects forecasts in the evening, the low temperature forecasts are for 12 hours later than the high temperatures. Therefore, the low temperature forecasts are for a half-day further out than the highs. Think of it this way. The high temperature usually occurs in the late afternoon, around the time ForecastWatch collects its forecasts. So a one-day out high temperature forecast will occur in about 24 hours. The low temperature forecast usually occurs in the early morning. So a one-day out low temperature forecast for tomorrow actually will occur in the morning of the day after tomorrow, about 12 hours after the high.

What is the difference between accuracy and skill?

Accuracy measures how close a weather forecast is to what actually happens. But it doesn't tell you anything about how skillful that weather forecaster is. That is an important difference. Because if you never predict rain, in most parts of the country you will have an accuracy of 70% or so. Skill measurements try to quantify how much better a weather forecast is than chance, or unskilled forecasts like climatology or persistence forecasts. ForecastWatch can help you create an accuracy or skill measurement that will help you evaluate or quantify the value of your weather forecasts.

What are "climatology" and "persistence" forecasts?

You might be interested in the more advanced services ForecastWatch provides! In addition to providing the percentages used here at ForecastAdvisor, we also do advanced accuracy and skill calculations. Climatology weather forecasts are forecasts which predict that the weather will match climate averages. Persistence weather forecasts are forecasts that predict that tomorrow, and the next day, and so on will be exactly like today. These are considered "unskilled" forecasts, as it doesn't take any skill to produce. They are used to help calculate the skill of weather forecasts produced by meteorologists.