1988 Buick Regal runs hot

Iam trying to find out if anyone could help me. I have a 1998 bucik regal ls, 3.8 v6, Low miles. Very nice car but it just started to run hot. When driving and stoped at a light it will reach to about 220-then goes to the red. I turned off the A/C, turned on the heater but did not get hot insjde, heater not very hot, but did not bring down the temp gauge,
What could it be, a temp switch?
could someone please get back with me.
thank you.
luis, dallas tx.