Living in Hawaii I do have some climbing to do from time to time. My temp gauge fluctuates from 1/4 to about 1/2. When I am going up a mountain it will seemingly rise (quickly) to 3/4, after passing the apex of the climb it starts to settle back down. Is this normal behavior? What does the gauge usually sit at? So far I have not boiled over, etc, but this does cause me some concern.

the temp gauge is supposed to climb to the 12:00 o'clock position and stay there. most of the time when it moves around like you described without boiling over, there is a problem with the thermostat.

did your car had enough coolant when this stuff happened?

I haven't steamed out or boiled over. most of the time my gauge sits at the 1/4 to 1/3 position.

oops sorry, I seem to have enough water, tho I do want to drain and replace with anti-freeze.

The gauge should run about halfway normally.

I recommend replacing the thermostat. It could be stuck partly open, so you get slow warm-up, and overheating under load.

yeah like he said, if the gauge isn't making it up to the halfway then your t-stat is probably stuck open.

make sure you run 50/50 ratio of DISTILLED water and anti-freeze. People make 2 mistakes:

Too much antifreeze lowers the heat transfer capability of the fluid through the radiator and makes a car run HOTTER and overheat!

Too little anti-freeze and you risk internal corrosion.

Too little anti-freeze and you risk internal corrosion.

you florida guys don't really have to worry but too little anti-freeze with also cause coolant freeze-ups obviously.