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What the UTCI is?

Interpretation of the Universal Thermal Climate Index (UTCI)


Universal Thermal Climate Index (UTCI) shows the temperature felt by the human body under the influence of the simultaneous action of a whole set of meteorological factors, the so-called "perceptible temperature". This quantity, just like the air temperature, is given in degrees Celsius.

The UTCI is based on a human heat balance analysis. It is defined as the equivalent air temperature, at which, under reference conditions, the basic physiological parameters of the body take the same values as under real conditions (1).

UTCI Classes
Index Value Heat stress characteristics Recommendations
above +46°C extreme heat stress Necessary periodic cooling of the body, necessary replenishment of fluids in the amount of more than 1/2 litre per hour. Avoid heavy physical exertion.
+38 to 46°C very strong heat stress Necessary periodic use of air-conditioned rooms or shaded areas, necessary replenishment of fluids in excess of 1/2 litre per hour. Physical exertion must be limited.
+32 to 38°C strong heat stress Necessary fluid replenishment of 1/4 litre per hour, desirable use of shaded areas and periodic reduction of physical exertion.
+26 to 32°C moderate heat stress Necessary replenishment of fluids at a rate of 1/4 litre per hour.
+9 to 26°C no thermal stress No inconvenience associated with overcooling or overheating of the body (physiological processes of thermoregulation are sufficient to maintain thermal comfort).
0 to 9°C slight cold stress The use of gloves and headgear is desirable.
-13 to 0°C moderate cold stress Exercise should be increased and limbs and face should be protected from cooling.
-27 to -13°C strong cold stress Exercise should be increased and limbs and face should be protected from cooling. Increase thermal insulation of clothing is desirable.
-40 to -27°C very strong cold stress Exercise should be increased and limbs and face should be protected from cooling. It is necessary to increase the thermal insulation of clothing and limit the time spent outdoors.
below -40°C extreme cold stress Keep the length of stay to a minimum. Necessary increase in thermal insulation and windproofing of clothing.

1. Radzka U., Dragańska E. "Bioklimatyczne warunki turystyki i rekreacji w województwie warmińsko-mazurskim", Olsztyn 2015