We do not have any official extreme temperature ratings for the camera.
In colder temperatures, the main concern is reduced battery life. The HD HERO does generate heat during operation to help keep the battery pack from getting too cold and therefore helps to minimize the reduction in run times. The HD camera does include a rechargeable lithium ion battery pack, which is the type to hold up best in cold temps.
In hot temperatures, the HD HERO cameras will automatically shut off if operational temperatures exceed 125 F.