I am not one of the more mechanical people here, but something sounds wrong. Does your fan come on? How long has it been since you’ve had a radiator flush?

 

The engineers designed the JK cooling system fan to come on at approx. 224-226 degrees, unless the A/C is on then it get a signal to come on when the pressure hits its set point. Now the cooling fan is a variable speed fan so the hotter the coolant temp, the faster the fan pulls air though the radiator. Like has been mentioned when was the last radiator flush? How many miles, last cooling system service, water pump, thermostat? Does your fan sound like an aircraft when your temps are close to 240 degrees? Is there anything in front of the grill to impede air flow (winch, lights, ect.) Mine runs anywhere from 195-220 (even in 100 degree temps) unless I'm going up a long hill or mountain, then it hits 230-240, but cools back down fast afterwards. Good Luck.

 

Mine runs about the same now that I am using a Mopar thermostat.

 

The only time my temp gauge moved off of the halfway point was when the thermostat stuck closed. This has happened twice to me. This is over 100K miles, with plenty of miles in the 100 degree range. I do have a manual though and they seem to run cooler than the autos.

 

Normal is never below the thermostat temp unless in very cold weather.

The thermostat is 203 degrees approximately starting to open at that temp and is fully open at 223 degrees. If not running the A/C the fan will come on at 226 degrees. With the A/C on the fan will pretty much be running on low fully time. As temp increase above 226 degrees fan speed will increase. By the time it gets to 240 or so it sound like a plane. Limp mode is 250. Normal temps should be between 203 and 226. In heavy driving maybe getting up to 235. I don't think I have ever seen temps higher than 235 and that is towing up a mountain pass.

More than likely it is a thermostat problem.

 

This is your answer. I put one on my JL and it dropped the temps about 20F in almost all circumstances.
RpmExtreme JEEP JK PWM FAN CONTROLLER - HEMI - 3.8 - 3.6 :: RPM Extreme

 

This is your answer. I put one on my JL and it dropped the temps about 20F in almost all circumstances.
RpmExtreme JEEP JK PWM FAN CONTROLLER - HEMI - 3.8 - 3.6 :: RPM Extreme

What were your average temps with the same given context of driving conditions as my example before the fan controller?

And for others, no mods as stated except for tires and oem hard top.
car has around 65k miles and and not sure when the last cooling service was done as didn't get it from new but after having a lot of cars, unless there were leaks or cracks in the cooling system which there isn't one that I know of, I would think a coolant flush would be an outlier scenario where it's affecting the average coolant temperature. Not to say it wouldn't be out of the question but looking for the more likely scenarios first. Unless a prolonged coolant flush has been known to raise average coolant temperature for these cars which I haven't heard of at least before on other cars.

 

FSM says stock jk thermostat on a 3.6 starts to open at 195f. This summer running in mid 90's temps fully warmed up in Ky my 2013 would be between 210 and 220 on the jscan trail view rolling down the highway 50-60 mph. If I parked in a parking lot with ac running it would go on up to 227-230 and the fan would speed up some and bring it down a few degrees then move back up. Have never seen above 240 ever no matter the operating conditions, speed, or outdoor temps.

 

Never seen above 226.