[3] The lake is bordered by the steep summits of the Mont du Chat and the Chaîne de l'Épine on the west, and Bauges Mountains on the east, which form its shores.

It is mentioned in particular in the donation made by the Count of Savoy Amédée III in 1125, for the foundation of the abbey of Hautecombe, "on the shore of the lake of Châtillon" (supra ripam loci de Castellione).

Lake Bourget features an oceanic climate (Köppen: Cfb), like most places in Western Europe.

In spite of this, it is highly influenced by its interior position within France near several mountain ranges, resulting in quite hot summers and cool to cold winters with frequent temperatures below freezing, especially at night.

The nearest weather station is located at Chambéry Airport, less than a mile south of the lake.