Engine temp

Greetings all I am seeking a second opinion to myself on an issue with my vehicle
I have a 2000 GrandPrix GT (3.8L) 145K . Well my issue is that it seems to be running very cool. Once again this morning I let it idle for about 20 min before I left for work because the engine temp barely gets above 160 degrees. Granted it has been COLD outside (single digits to 0), but I would think it sitting on idle for that kind of time would bring the temp up. I have double checked the coolant level, and it appears to be between the markings of cold and hot on the overflow resivior. And I do have heat inside the vehicle but seemingly not as much as I should. Could I be looking at a possible thermostat that is needing replacement or should I be digging deeper?
Thanks anyone for advice on this matter.

Sounds like a thermostat. But make sure it is a 195 degree.

With the colder temps I believe we are all running cool.

Welcome to the forum.

I had the exact same problem. I have a 1994 GTP with 3.4 DOHC, so we have different motors, but I changed my thermostat (180 degree) and it improved my problem, but my temp. won't go up above the first mark for anything. I'm gussing it stays about 150-160, which is pretty close to 180. You should try that first, especially if it has never been changed. Make sure you follow the upper radiator hose, that will lead you right to it. The part should not cost more than $10.