Hi an sorry for my bad english
It seems to be a bad temperature-sensor, or a bad wire in this section. Perhaps one of the cooling-fan relaise is bad.
Your Watertemparature-Gauge is controlled direktly from the engine-Electronic, so I think your Problem is the Engine-Temperature-Sensor or its Wire. Please take a look at the cable-connector. If this isn´t clean: Clean it.
If it´s clean and the cable seem okay please renew the Sensor!