Overheating?!

So i pick up my car from the long term parking lot in Denver (it had been sitting for appx. 10 days). Starts fine...then i get on my way and i notice the water temp gauge is higher than normal. I pay close attention to it and its goes up to right below the red, i throw the climate control on and its fine for the next 2 hours of driving, right in the middle where it should be, only revealing the bottom half of the top wave on that little icon(my eyes were fixerd to the gauge for 2 hours). I figured maybe something was screwy before so i turned the climate control off when i got home and the same thing started to happen. The temperature of the air blowing didnt seem to affect it at all, just that it was on. I know putting the heat on is supposed to help the car if its overheating, but not to this extent and for such a long period of time. Is my water pump going? Do i need a new johnson rod or rotater splint? This whole thing is making me very upset, and damnit, i dont like being upset!
any ideas?

-Alex