Temperature Gauge Fluctuating

Thank you very much for the diagnostic suggestions. I will definitely give it a try today as i intend to drive a fair distance. Regarding the climate, I live in san diego where the climate is fair almost all year long. As far as the frequency of the problem, it happens intermittently without any specific pattern. Also, what could explain the P0116 (engine coolant temperature circuit high voltage) error code that i received before?