Mine does the same thing...almost. I at least get to the second bar. You could try to replace the temp gauge sending unit, but in my case it didn't help. The factory gauges are notorious for being inaccurate. There's no real way to trim(adjust) them.
You're choices as I see them are limited to living with the guestimate on the factory gauge or installing an aftermarket gauge somewhere. My car is down right now while I finish the turbo motor build, and when it hits the road again, it's got the full gauge treatment. I purchased gauge panels from Florida 5.0 that installs in the place of the factory cluster and another that mounts in the notch on the dash that runs from the cluster to the right hand speaker and I've bought a full complement of Stewart Warner gauges including speedometer and tach to get away from the factory gauges.
You don't have to go as far as I have, but a simple 3 gauge panel or even an individual temp gauge would put you in better shape than the factory stuff. They're animated idiot lights at best.