The Miami Valley is under a Heat Advisory until 8 p.m. Monday.
With a heat index of 100 degrees outside, it's making any prolonged work outdoors dangerous.
Little ones and their families at Orchardly Park were staying cool by staying in the water Monday and also remaining hydrated.
LOCAL: First Heat Wave of 2018?
But some people weren't playing in the sun. They were working and working to keep cool.
Tree trimmers were in Riverside Monday morning, cutting down limbs around the Valley Worship Center on Valley Pike.
Trimmers started the work at 9 a.m. and planned to be there for five to six hours.
"We've been working for about an hour and a half now and I'm already hot," said Josh Patterson, tree trimmer for Tackett Tree & Shrub Service.
Patterson said he's never experienced heat exhaustion on the job.
"I've been doing it so long, you just get used to it."
Thankfully, their bosses have seen to it that their coolers are overflowing. They filled coolers with ice and drinks to keep their core temperatures down.
LOCAL: 1 killed in crash on Halderman Road, Preble County; OSP investigating
But in the ER at Kettering Medical Center, this time of year doctors see an influx of patients suffering from the sun.
"We see everything from heat-related cramps so severe you can have abdominal pain, cramping, sometimes you'll have severe nausea and diarrhea," said Dr. Nancy Pook, medical director of Kettering Medical Center Emergency Department. "It doesn't make sense right, but when you're body is shutting down sometimes different people act differently."
Kettering lacrosse players were practicing in the heat from 8 to 11 a.m. Monday.
Dr. Pook said they're fine as long as they take plenty of water breaks in the shade.
But in this heat, she said it's better to get all outdoor work done in the coolest parts of the day, either early morning or late evening.
"People with respiratory problems out in the heat really get into trouble with difficulty breathing," said Dr. Pook. "We watch out for our cardiac patients because lots of them are on diuretics, so pills that decrease their fluids inside anyway."
Kids under the age of 4 are also at risk because their bodies can't properly regulate their temperature yet.
Parents at Orchardly Park's splash pad had the right idea, keeping their children in the cool water.
LOCAL: Heat and Air Pollution Advisory into the evening
The workers at Tackett Tree & Shrub Service said they're going to have to focus on getting their job done as quickly as possible.
"A lot of times if it's too hot we'll hurry up and finish that job, move on for the day and go home," said Patterson. "But nine times out of 10, you just try to stay positive and push through."
Dr. Pook also said that you want to take breaks in air conditioning, as you can bring your core body temperature down.