Cold
Air temperature – Cold
In the case of extremely cold air temperatures, a combination of air temperature and wind is considered in determining the impact on people. This factor is known as “wind chill” (WET = wind chill equivalent temperature) and describes the cooling effect of the wind, especially in the case of low temperatures.
If there is no wind, then the wind chill is the same as the air temperature. The faster the wind speed however, the colder it is relative to the air temperature.
As soon as the wind chill reaches -10°C or colder the hour is a bad weather hour. If three such hours occur in a row, the rest of the day is deemed bad weather.
The table below shows how the combination of air temperature and wind speed affects the felt temperature. At the indicated wind speed, the wind chill temperature reaches -10°C and lower.
| Air temperature in °C |
Minimum wind speed km/h |
| -1 | 18,4 |
| -2 | 16,2 |
| -3 | 14,4 |
| -4 | 12,6 |
| -5 | 11,2 |
| -6 | 10,1 |
| -7 | 9,0 |
| -8 | 8,3 |
| -9 | 7,2 |
| -10 | 0,0 |
Example: If it is -1°C and the wind is blowing at 18.4 km/h or faster, then people will perceive the temperature as being -10°C or colder.