Car heat gauge going over midline where it's never gone

[N-OS X-tasy!]

Carm wrote:
[quote=Dennis S]
About how long does it need to cool before I can take the radiator cap off?

Squeeze one of the hoses, if the pressure is high it won’t have any give. If it cooled down enough you can squeeze without much pressure on the hose.
Plus if you burn yourself grabbing the hose, you'll know it's too soon to remove the cap.