Heat and humidity have first responders concerned, as thousands of spectators make their way to Southern Hills for the PGA.
They said the last two days have already been hot enough for a few cases of heat related illness, and it's only expected to get warmer.
This isn't Kim Sherrod's first time at a PGA championship - and she's prepared for the heat.
"You can bring one unopened water jug; I would suggest that," she said.
Sherrod brings extra water, sunscreen, and a plan for who to call if she starts to feel faint.
That planning is exactly what Tulsa Fire Department Paramedic Conrad Collinson likes to see.
"Prepare yourself so that when you're out here you're not already behind the eight ball," he said. "If you know you're going to come out this weekend, go ahead and start hydrating yourself now."
Collinson said you should expect a lot of walking across hot pavement on your way in. Although there's plenty of shade, several people have already been treated for heat exhaustion.
In advance of warmer weather, the PGA set up a first aid tent on the course and has several crews of paramedics on standby.
"We have six crews from the Tulsa Fire Department, six crews that are strategically located throughout the golf course," Collinson said.
A final piece of advice from Sherrod is to keep an eye on the people around you.
"People need to watch out for everybody when it gets kind of muggy for heat stroke, heat exhaustion, those kinds of things," she said.
Saturday will likely be the coolest day to head out - but Wednesday and Thursday will be in the 90's and sunny - so bring plenty of water!