Need a Car Doctor 2000 Pontiac Firebird Overheating Issues...?

My cars temp has never raised above the 210 until recently, now when i'm in traffic the needle goes past it and almost redlines... I have also noticed that recently my heater will work fine on the freeway but when I get off the freeway and get into commute traffic the heating air turns cold. My questions are; 1) What could be causing these problems, 2) Are they related, 3) What can I do to fix them? Thanks