How hot is too hot?

[phook]

I'll be attending my first track day event tomorrow and wanted to know what to look for on my engine temperature gauge.

I have a 2000 base and the car is stock. I've been to about 5-6 autocross events so far, and have seen the temperature go a tiny bit past the '0' on the '180' numbering on the temperature gauge. That is usually on hotter days during the fun run parts of the day where I might hit about 6-7 laps in a row.

Since I will be on track for a much longer period then autocross and at higher speeds, what should I look for to know to maybe stop and cool down a bit? Temperature is expected to be about 93 tomorrow at the track.