Wind Chill Temperature Index

What is Wind Chill Temperature?

It is the temperature it "feels like" outside and is based on the rate of heat loss from exposed skin caused by the effects of wind and cold. As the wind increases, the body is cooled at a faster rate causing skin temperature to drop. Wind Chill does not impact inanimate objects like car radiators and exposed water pipes, because these objects cannot cool below the actual air temperature.

What does this mean to me?

The NWS will inform you when Wind Chill conditions reach critical thresholds. A Wind Chill Warning is issued when wind chill temperatures are life threatening. A Wind Chill Advisory is issued when the wind chill temperatures are potentially hazardous. These hazardous wind chill temperatures could lead to life-threatening situations, if caution is not exercised.

When are Wind Chill Warnings and Wind Chill Advisories issued?

The National Weather Service issues wind chill advisories when the wind chill temperature reaches -10° F to -24° F for more than a few hours with winds of 10 mph or greater. Wind chill warnings are issued when wind chill temperatures reach or exceed values of -25° F and colder for more than a few hours with winds of 10 mph or greater.

Click on http://www.weather.gov/os/windchill/images/windchillchart3.pdf for a clearer chart.

The wind chill temperature index:

• Uses wind speed calculated at the average height of the human body’s face (five feet), instead of 33 feet (the standard anemometer height).
• Incorporates modern heat transfer theory (the body loses heat to its surroundings during cold and windy days).
• Lowers the calm threshold to 3 mph.
• Uses a consistent standard for skin tissue resistance.
• Assumes the worst case scenario for solar radiation (clear night sky).