2002 Jeep Grand Cherokee overheating

Do you see coolant on ground? Plenty of coolant in radiator, overflow bottle? Coolant at proper 50/50 mix? Is the temp gauge working correctly? Does this only occur when idling and not moving/moving slowly, but then is OK when driving (temp gauge goes down)?
If only when not moving/moving slowly, add the electric cooling fan to your list of possibilities - it's controlled by the coolant temperature switch. If the temp goes high but fan not kicking on, check fuse and/or relay for "Aux. Fan" or "radiator Cooling Fan" see owner's manual for locations. Also, fan may have bad plug connection or broken wire.
The most common causes of overheating besides Fan:
1. Not enough Coolant.
2. Loose /damaged Drivebelt (drives water pump).
3. Clogged radiator.
4. Bad thermostat.
5. Radiator Fan(s) not working properly.
6. Radiator cap not holding pressure.
7. Bad water pump.
8. Ignition timing is out of adjustment.
9. Wrong grade of Engine Oil (Check owner's manual for Recommended Grade).
10. Temp. Gauge is not accurate.
YEE-Haa! Hope this helps!