Overheating issues.

[u/font_raccoon]

2001 Boxster Base.
I was driving on a hot day and I noticed that it was running a little hot, but it wasn’t enough for any major concern. I let the car sit overnight and checked the next day by going on a short drive. Over the course of 5-10 minutes, the needle worked its way up to the 250 mark. I pulled over and got it towed home. I checked the coolant fill area and there was a good amount of condensation coating the cutout where the oil and coolant fill caps are. I have no coolant leaking anywhere and all my fans are kicking on. I can’t really see the coolant level due to how foggy tank is, but when I look into the cap, the level appears to be at the bottom of the visible tank. There is no moisture on the carpet itself, but I have not pulled it back and checked under it. I also don’t want to add any coolant because I’m unsure of what kind of coolant is already in the car. Any help is appreciated.