It’s been the Rock Hill region’s hottest July in 3 years. What’s next?

Another day of 90-degree-plus temperatures will close what has been a hotter-than-average July for the Rock Hill area.

But forecasters say a changing pattern will mark the beginning of August, with a slight cool down and increased chances for rainfall.

Afternoon highs in the low 90s are forecast for Wednesday, and that’s in line with the average high of 91 degrees this month at the airport in Rock Hill. Typically, afternoon highs average 89-90 degrees for the area.

National Weather Service records indicate this will be the hottest July in three years, with a daily average (combining the highs and lows) of 81.6 degrees. That’s nearly 3 degrees above the typical July average.

All that will change later this week, forecasters say.

The Carolinas will be caught in an area of atmospheric weakness between two strong high pressure systems -- one near Bermuda, the other over the U.S. Southwest. That weakness in the atmosphere will open the gates for moisture to stream into the region from the Gulf of Mexico and Caribbean.

Thunderstorm chances will ramp up Thursday, says National Weather Service meteorologist Rodney Munroe, and by Friday, the storms could contain some heavy rain.

“The environment Thursday looks to be fairly supportive for stronger thunderstorms to develop,” says Munroe, adding that damaging wind gusts would be the main threat.

“There also will be an increasing threat of at least minor flooding Thursday into Friday, as storm movement will be slow,” Munroe says.

The additional clouds will temper afternoon temperatures a bit, holding highs to the upper 80s from Thursday through the weekend. But humidity levels will be high.

The unsettled weather pattern is expected to continue into next week, forecasters say.

Steve Lyttle on Twitter: @slyttle