http://www.atc.army.mil/weather/windchill.pdf

Less than 45 min on exposed skin, according to that chart. When I FEed in Deadhorse I wore a headsock, thick knit hat with wind block, and ski mask when I was outside. Of course I over dress in comparision to a lot of the natives, I guess you can take the Californian out of California, but you can't take the California out of the Californian