I've never understood the antipathy towards weathermen. Culturally, everyone seems to agree: You can't trust the guy on TV telling you whether it's going to rain. He's always wrong. Or at least often wrong. And yet, I call up the forecast pretty much every morning, and while I wouldn't say it's never been wrong, it's not wrong all that much. 

Matt McClain/Washington Post

But then I read the excerpts of Nate Silver's new book on probabilistic thinking, and it all made sense. It's not that the weather forecasts are off. It's that the weather guy is lying. I just didn't notice because I only check the weather online. 

For many years, the Weather Channel avoided forecasting an exact 50 percent chance of rain, which might seem wishy-washy to consumers. Instead, it rounded up to 60 or down to 40. In what may be the worst-kept secret in the business, numerous commercial weather forecasts are also biased toward forecasting more precipitation than will actually occur. (In the business, this is known as the wet bias.) For years, when the Weather Channel said there was a 20 percent chance of rain, it actually rained only about 5 percent of the time.

People don’t mind when a forecaster predicts rain and it turns out to be a nice day. But if it rains when it isn’t supposed to, they curse the weatherman for ruining their picnic. “If the forecast was objective, if it has zero bias in precipitation,” Bruce Rose, a former vice president for the Weather Channel, said, “we’d probably be in trouble.”

So that's the answer, then. The problem isn't the weather forecast. The weather forecast is fine. The problem is the weatherman. And, more than it's the weatherman, it's the economics of the whole sell-advertising-by-telling-you-about-the-weather model.

 In his essay "The Braindead Megaphone," George Saunders writes that saying "tell us the truth" is not the same thing as saying "tell us as much truth as you can while still making money." It serves everybody's purposes to pretend it is, but it isn't.