Jeff Swackhammer spent Saturday morning doing some yard work, unbothered by the heat advisory covering the region.

“It was totally fine,” Swackhammer said.

But then, as the weekend continued, the dreaded warmth arrived in earnest. By Sunday afternoon, when the Mars man hosted a company picnic at Alameda Park for Swack Business Group, he was up to his eyes in sweat.

“It was very hot,” he said. “Mid to low 90s. We handed out water balloons and misters. Eventually, I had to run to the store and get double the water and ice we planned on.”

Swackhammer's weekend was likely a common weather story for other Butler County residents.

While county heat indexes met the warned-of levels by 4 p.m. Saturday, the day's beginning brought unexpected cloud cover that dampened the feared weather.

Myranda Fullerton, a meteorologist for the National Weather Service's Pittsburgh office, said an overcast Saturday morning temporarily spared the area.

“Cloud cover kind of stalled the heating throughout the day,” Fullerton said. “It really hit in late afternoon.”

At Moraine State Park, she said, a Saturday heat index report showed a 104 high around 4 p.m. Another Butler County monitoring site hit 101, she said.

“We did meet our heat advisory threshold with those heat index values,” Fullerton said. “I think people get a little rustled because the actual temperature level was high 80s and low 90s.”

The weekend's dangerous heat, she said, was actually all about the very high humidity. Humidity percentages remained in the upper 90s for much of the weekend, Fullerton reported.

“This wasn't going to be a record breaking heat in terms of actual temperature,” Fullerton said. “But it's been very humid.”

Butler County is expected to cool off some for the rest of the week, after a period of roaming thunderstorms Monday and Monday night.

National Weather Service forecasts for the week on Sunday evening showed temperatures with daytimes highs in the 70s and nighttime lows in the 50s through Thursday, which is expected to have a daytime high in the low 80s.