Anna Answers: How accurate are long-range forecasts?

Weather Wisdom

Question: How accurate is long-range forecasting before an event or a storm?

Answer: Meteorologists know when a significant weather event is likely to occur. But we know this a lot of times are up before the event. Now we use weather forecasting models and other tools to help us make our forecast. And further out before the event, there’s actually a lot of unknowns.

For example, If we are forecasting for an event 10 days out before this event. There’s a lot of different possible solutions. This is because forecasts models are based on current conditions and current conditions are always changing. As these current conditions change, our path changes as well.

Now, despite all the possibilities, a model only models one possible solution, each model run only gives you one look at how a solution could play out. As the event nears, the current conditions and calculations will be more accurate closer to the event. The closer we are to the weather event, the more accurate a forecast is. Even though we have an idea, something significant is going to happen farther out before it actually happens.

In summary, a 10-day—or longer—forecast, is often not as accurate as a short-range forecast. Since we can’t collect data from the future, models have to use estimates and assumptions to predict future weather. The atmosphere is constantly changing, so estimates are less reliable further into the future.

Have a weather question you have always wondered about? Message me on social media: Facebook (Anna Meyers), Twitter (18StormAnna), and Instagram (, or email me at and you might be featured on the next weekly Anna Answers.

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