These function in hot and cold climates. In extreme frigid temps, if placing the panels at room temp before using (10 minutes), this allows optimal flexibility & contouring features. In severe heat & direct sunlight, we do not recommend leaving the panels on a vehicle with extreme surface temps for prolonged periods. (Overheated rubber material can deteriorate. Magnet strips will accommodate <120 degrees surface temps on vehicles. Hot sun for several hours may exceed max temp recommendation especially on a dark vehicle. Recommended to avoid prolonged periods on vehicle in high temps and sun, or long periods stored in trunk in high temps and direct sunlight on trunk.)