Measurements · Meteorology
Wind Chill
Also known as wind chill temperature
Wind-chill (apparent cold) temperature.
What it is
What is wind chill?
Wind chill is a derived index that expresses how cold the air feels on exposed skin once wind is taken into account, reported as an equivalent temperature in degrees Celsius. Moving air strips away the thin insulating layer of warmed air next to the skin and accelerates convective and evaporative heat loss, so a given air temperature feels progressively colder as wind speed rises. The wind-chill temperature is calculated from air temperature and wind speed using a standard formula, such as the North American model adopted by Environment Canada and the US National Weather Service, and it applies only at low temperatures, where cold-weather heat loss is the concern.
Health and operational effects
Wind chill matters because it, not the raw thermometer, predicts the risk of frostbite and hypothermia for people working or exercising outdoors in the cold. As the wind-chill value falls, exposed skin can freeze in progressively shorter times, and cold stress impairs dexterity, judgment, and endurance long before it becomes life-threatening.
For employers, expedition and event organizers, and the military, wind chill is the basis of cold-stress management: setting work–rest cycles, mandating protective clothing and shelter, limiting exposure time, and, at the extreme, halting outdoor work. It is the cold-weather counterpart to heat-stress indices, and like them it converts a combination of conditions into a single actionable number that a bare temperature reading cannot provide.
How it is measured
How Wind Chill Is Measured
Wind chill is not measured by a dedicated sensor but calculated from two measured inputs: air temperature and wind speed. So a wind-chill monitor is really an accurate air-temperature sensor in a radiation shield combined with an anemometer, with the index computed from both readings. The quality of the result depends on both inputs. In particular, the wind speed must be measured at, or corrected to, the standard reference height the formula assumes, and the temperature sensor must be properly shielded from radiant heat. Because it is derived, wind chill is only as reliable as the two instruments feeding it.
An instrument on Thiamis3
A third-party instrument connected to a Thiamis gateway, reporting into the same Environet account.
Placing wind chill monitoring
Site the underlying sensors to represent the conditions people actually experience: the temperature probe in a ventilated radiation shield and the anemometer in clean, unobstructed exposure, both away from buildings and heat sources that would distort either input. Where the concern is a specific exposed work area, position the instruments in the same wind and cold the workers face rather than in a sheltered spot. Local shelter can make the real-world wind chill milder (and a wind funnel can make it harsher) than a nearby reference reading suggests.
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Questions
Wind Chill FAQ
What is the difference between wind chill and air temperature?
Air temperature is the physical temperature measured by a shielded thermometer; wind chill is a calculated value that lowers it to reflect how much faster wind makes exposed skin lose heat. Wind chill is always at or below the air temperature and only applies in cold conditions.
At what wind chill does frostbite become a risk?
Risk rises steeply as wind chill falls well below freezing, with frostbite on exposed skin possible within tens of minutes at moderately low values and within minutes at extreme ones. The exposure-time bands on this page pair each wind-chill range with an estimated time to frostbite, which is how cold-safety protocols are triggered.
Is wind chill measured or calculated?
Calculated. It is derived from two separate measurements (air temperature and wind speed) using a standard formula, so there is no single "wind-chill sensor". Its accuracy depends entirely on a well-shielded temperature reading and a properly exposed wind measurement.
How do I monitor wind chill?
Wind chill needs both temperature and wind, so pair a Thiamis gateway with an external weather station providing an anemometer and a shielded temperature probe; the index is then derived from the two. Use the configurator to combine wind chill with wind speed, wind direction, and precipitation for a full cold-weather site-safety picture.
Monitor Wind Chill on the Record
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