Is there any way to to bring the cooler air to the third floor?
I have central air, no basement, the first and second floors are cool but my floor, the third floor is hot.

I would look for balancing dampers in the duct work.

It is not easy for a homeowner to fix this issue. Your system must be evaluated to insure there is enough BTU and air volume for your square footage and then they move to the fix. You need sufficient hot air return from the third floor as well as cold supply. Dampers and balancing should help but the problem starts with poor HVAC design when it was built.

Pushing heavier air up 3 stories to cool a floor can be a challenge, particularly if you have a lot of solar load on the roof. I would first try to close the first floor dampers a bit and see what happens. You could also crack the top of the 3rd. windows a bit to see if it will bleed out the hotter air.