Temperatures can drop well below zero in Montana during the winter. The wind chill factor can make those temperatures feel much colder.

Wind chill is a term commonly used by meteorologists in the colder months of the year. But, when you see a wind chill of minus 20 degrees in your forecast, do you know what that truly means?

National Oceanic and Atmospheric Administration

You can determine your wind chill temperature using the chart above. Find the value closest to the outside air temperature, then the value that is closest to the current wind speed. Your wind chill temperature is the value where the lines drawn from the air temperature and the wind intersect.

The blue-shaded areas in the wind chill chart represent the amount of time it takes to get frostbite at the corresponding wind chill temperatures.