alfa romeo 146 overheating then going down?

hi ya my alfa romeo keeps getting to 120 degrees that is max but the over heating light dosent come on. then it will fall to 100 degrees sometime it differs but the car drives very well with no faults and when i open the bonnet then engine isnt hot at all. if anyone has any idears please let me know as i dont think is safe being that hot allthough theres no engine lights on and it drives very well.

it a 1996 alfa romeo done 52,000 miles with full service history and its in lovey conditon.

just thought id mention that thanks again