Wind Chill Calculator – How cold does it really feel?
The wind makes us experience it as colder. But what is the actual impact? Freeride clears up once and for all how a stormy weather affects the perceived cold.
You have probably heard or read about it in some form of weather report – the perceived temperature versus the actual temperature on the thermometer. But what does this actually mean?
Often, we check the thermometer before we go out and dress as best we can based on the information we have. But the thermometer doesn’t always show the whole truth. In fact, there is another parameter to consider in order to create a correct picture of the weather – the wind. As soon as it starts to blow outside, the wind’s effect is added with a cooling effect.
When the sun beats down during the summer, a refreshing wind can be nice. But in the winter, it can feel really cold when the wind is blowing. Therefore, it is important to keep an eye on the wind to dress appropriately, which becomes extra important in the ski slopes or in the mountains where you often stay outside for a long period of time. The risk of cold injuries also increases when it is windy outside.
Greater effect at low temperatures
Wind chill or cold index (often referred to as wind chill effect) is a meteorological term for how the skin temperature is affected by the surrounding temperature in combination with wind speed. It is especially at low temperatures that high wind speeds have a greater cooling effect than what the thermometer shows. For example, if the thermometer shows 14°F and there is a wind of 22.37 mph, which is not uncommon in mountain areas, it can be said that the wind’s cooling effect corresponds to 10.12°F at calm wind.
Below you can calculate the perceived temperature with a calculator and see the table how the wind affects the temperature that the thermometer shows.
Wind Chill Chart
| Wind | 40°F | 30°F | 20°F | 10°F | 0°F | -10°F | -20°F | -30°F | -40°F |
| 5 mph | 36 | 25 | 13 | 1 | -11 | -22 | -34 | -46 | -57 |
| 10 mph | 34 | 21 | 9 | -4 | -16 | -28 | -41 | -53 | -66 |
| 15 mph | 32 | 19 | 6 | -7 | -19 | -32 | -45 | -58 | -71 |
| 20 m/s | 30 | 17 | 4 | -9 | -22 | -35 | -48 | -61 | -74 |
| 25 mph | 29 | 16 | 3 | -11 | -24 | -37 | -51 | -64 | -78 |
| 30 mph | 28 | 15 | 1 | -12 | -26 | -39 | -53 | -67 | -80 |
| 35 mph | 28 | 14 | 0 | -14 | -27 | -41 | -55 | -69 | -82 |
| 40 mph | 27 | 13 | -1 | -15 | -29 | -43 | -57 | -71 | -84 |
| 45 mph | 26 | 12 | -2 | -16 | -30 | -44 | -58 | -72 | -86 |
| 50 mph | 26 | 12 | -3 | -17 | -31 | -45 | -60 | -74 | -88 |
| 55 mph | 25 | 11 | -3 | -18 | -32 | -46 | -61 | -75 | -89 |
| 60 mph | 25 | 10 | -4 | -19 | -33 | -48 | -62 | -76 | -91 |
Mathematical formula
In 2001, an extensive project was conducted under the leadership of American Randall Osczevski and Canadian Maurice Bluestein, with the goal of obtaining a correct formula for the perceived temperature. It was based on how people responded to different wind chill levels by using test subjects equipped with temperature sensors.
The formula is written as follows:
The wind chill temperature is calculated based on both the actual air temperature and the wind speed.
Wind Chill (°F) = 35.74 + 0.6215T – 35.75(V^0.16) + 0.4275T(V^0.16)
Where T is the actual air temperature in °F and V is the wind speed in mph.
How does this work?
Around the skin there is a thermal boundary layer of air. This layer insulates the skin from external temperatures. In practice, we feel the air as colder than it is when there is no wind because the wind causes parts of the insulating layer to disappear. In a warm environment, it works the opposite way; if you blow on your arm in a sauna, the area you blew on becomes very warm instead, because the insulating layer also helps to protect the skin from heat.
In reality, people do not actually feel the temperature of the air, but the temperature of the skin that decreases when exposed to a cooler environment.
Can wind make water freeze faster?
It is sometimes debated whether wind can cool water so that it freezes. It has been shown that wind can indeed have effects that promote ice formation. The wind itself does not change the air temperature, and therefore, no ice formation occurs as a result of the wind. However, ice growth can occur on the underside of an already ice-covered water surface through wind promoting the evaporation of water on the ice or sublimation of the ice, which also cools the underside of the ice and, thus, ice growth can occur. This effect is so great that growth can also occur at single-digit positive temperatures if it’s windy.
The first research on wind chill
The first people to develop a formula for calculating wind chill were American scientists Paul Siple and Charles Passel, who conducted an experiment in Antarctica in 1940. Simply put, the researchers calculated how long it took for water in small plastic bottles to freeze at different temperatures and wind speeds and then developed a mathematical formula for this.
Their research has long been used to estimate the cooling effects of the wind. However, this method has several limitations, including because it does not necessarily show how people react to the cold.
Text: Petter Elfsberg
