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Winter Storms
Plan. Equip. Train

To prevent injuries, illnesses and Fatalities during winter storms.

Wind Chill Temperature: A Guide for Employers

Winter Weather

Outdoor workers exposed to cold and windy conditions are at risk of cold stress, both air temperature and wind speed affect how cold they feel. Wind Chill is the term used to describe the rate of heat loss from the human body, resulting from the combined effect of low air temperature, and wind speed. The Wind Chill Temperature is a single value that takes both air temperature, and wind speed into account. For example, when the air temperature is 40°F, and the wind speed is 35mph, the wind chill temperature is 28°F; this measurement is the actual effect of the environmental cold on the exposed skin.

National Weather Service (NWS) Wind Chill Calculator: With this tool, one may input the air temperature and wind speed, and it will calculate the wind chill temperature.

Cold Stress Can be Prevented

It is important for employers to know the wind chill temperature so that they can gauge workers’ exposure risk better and plan how to safely do the work. It is also important to monitor workers’ physical condition during tasks, especially new workers who may not be used to working in the cold, or workers returning after spending some time away from work.

The National Oceanic and Atmospheric Administration (NOAA) Weather Radio is a nationwide network of radio stations broadcasting continuous weather information from the nearest NWS office. It will give information 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 wind chill temperatures are potentially hazardous.

 

The American Conference of Governmental Industrial Hygienists (ACGIH) developed the following Work/Warm-up Schedule for a 4-hour shift takes both air temperature and wind speed into account, to provide recommendations on scheduling work breaks and ceasing non-emergency work.

Blizzard Warning: Issued for sustained or gusty winds of 35 mph or more, and falling or blowing snow creating visibilities at or below 1/4 mile; these conditions should persist for at least 3 hours.

Wind Chill Advisory: Issued when wind chill temperatures are expected to be a significant inconvenience to life with prolonged exposure, and, if caution is not exercised, could lead to hazardous exposure.

Wind Chill Warning: Issued when wind chill temperatures are expected to be hazardous to life within several minutes of exposure.

Winter Storm Warning: Issued when hazardous winter weather in the form of heavy snow, blizzard conditions, heavy freezing rain, or heavy sleet is imminent or occurring. Winter Storm Warnings are usually issued 12 to 24 hours before the event is expected to begin.

Winter Storm Watch: Alerts the public to the possibility of a blizzard, heavy snow, heavy freezing rain, or heavy sleet. Winter Storm watches are usually issued 12 to 48 hours before the beginning of a Winter Storm.

Winter Weather Advisories: Issued for accumulations of snow, freezing rain, freezing drizzle, and sleet which will cause significant inconveniences and, if caution is not exercised, could lead to life threatening situations.

Printer Friendly Version
Work/Warm-up Schedule for a 4-Hour Shift

For a printable version of the Work/Warm-up Schedule, please print the PDF version that is available as a separate button/link on the web page.

Air Temperature -- Sunny Sky No Noticeable Wind 5 mph Wind 10 mph Wind 15 mph Wind 20 mph Wind
°C (approximate) °F (approximate) Maximum Work Period Number of Breaks Maximum Work Period Number of Breaks Maximum Work Period Number of Breaks Maximum Work Period Number of Breaks Maximum Work Period Number of Breaks
-26 to -28 -15 to -19 (Normal Breaks ) 1 (Normal Breaks ) 1 75 min 2 55 min 3 40 min 4
-29 to -31 -20 to -24 (Normal Breaks ) 1 75 min 2 55 min 3 40 min 4 30 min 5
-32 to -34 -25 to -29 75 min 2 55 min 3 40 min 4 30 min 5 Non-emergency work should cease
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-35 to -37 -30 to -34 55 min 3 40 min 4 30 min 5 Non-emergency work should cease
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-38 to -39 -35 to -39 40 min 4 30 min 5 Non-emergency work should cease
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-40 to -42 -40 to -44 30 min 5 Non-emergency work should cease
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-43 & below -45 & below Non-emergency work should cease

Schedule applies to any 4-hour work period with moderate to heavy work activity; with warm-up periods of ten (10) minutes in a warm location and with an extended break (e.g. lunch) at the end of the 4-hour work period in a warm location.

Adapted from ACGIH 2012 TLVs

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