Mirror Lake, Canada offers 1 beach perfect for sunbathing, surfing, swimming, and more. Mirror Lake, British Columbia, Canada, is known for its proximity to Kootenay Lake and the charming town of Kaslo. The best time to travel to Mirror Lake, Canada, is during the summer months of June to August, when the average air temperature is around 20°C (68°F) and the water temperature is approximately 15°C (59°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!