@hazydavy
The Windy default model (ECMWF) is a global model with a 9km resolution which is not very good for temperature prediction in mountains.
Selecting Reported temperature shows an official weather station near Visp. The Observation vs forecast tool confirms that you are right.
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But if you use other models with a better resolution like ICON-D2, METEOBLUE,AROME, the same tool shows that these models match quite well with temperatures reported by this weather station.
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So for temperature at Visp, try these weather models.