There is no doubt that Garda’s climate is mild. Yearly average temperatures are between 12°-13°, in fact snow and fog are rare north of Garda: the lake only froze once in history (1709).Relative humidity is of 66%; average water temperature is of about 21°, in depth (30 metres) it is about 13° (in September).here is no doubt that Garda’s climate is mild. Yearly average temperatures are between 12°-13°, in fact snow and fog are rare north of Garda: the lake only froze once in history (1709).