Good Question: What do rain chance percentages in the forecast mean?

LEXINGTON, Ky. (WKYT) - We’ve heard from a viewer who had a question about the weather radar, and now we’re hearing from one who wants to know about the numbers our meteorologists use.

Tammy asks, What does it mean when a meteorologist states there is a 40% chance of rain? Is it going to rain over 40% of the time, is it going to rain on 40% of the region, or is it just a general percentage?

Chief Meteorologist Chris Bailey says that number is referred to as the Probability of Precipitation, or PoP.

For WKYT, if we say there’s a 40% chance of rain tonight, it means we are confident that 40% of our coverage area will see at least 0.01″ of rain.

However, context is important for those numbers.

So, a 90% chance means most of you will see rain, but it doesn’t necessarily mean that it will be heavy. By the same token, a 10% chance may cover a small area, but it could be heavier for that area.

That’s why it’s important to listen to the forecast to get the full story on those numbers.

If you have a Good Question you’d like us to try to answer, send it to goodquestion@wkyt.com.

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