Rain during Oklahoma State fair isn't uncommon, state weather records suggest

That includes this year.

“It's like the old adage ‘It's going to rain, I just washed my car.' It's similar at fair time,” Dewald said. “In fact, someone in our office said earlier this week, ‘The fair starts Thursday, so it's going to rain.'”

And it did. Thursday marked the opening of the state fair, and Oklahoma City officially received more than a half-inch of rain, according to the National Weather Service, Norman Forecast Office.

So why does it seem rain and the Oklahoma State Fair are often linked in conversations?

Rainy season

Gary McManus, of the Oklahoma Climatological Survey, said some parts of the year in Oklahoma are naturally rainier than others. The state's rainy season occurs from April to mid-June.

“There is a secondary, but less active, rainy season in the fall, as well,” McManus said.

And for record-keeping purposes, climatologists and meteorologists consider fall as Sept. 1 through the end of November.

“So when talking about events such as the state fair in September, we're talking, climatologically speaking of course, about an increased chance of rain, since they do fall in our rainy seasons,” he said.

McManus looked at precipitation statistics from all Sept. 13ths from 1891 to 2012.

Although the Oklahoma State Fair hasn't been around that entire time period, Sept. 13 is a good general target date.