Universal Thermal Climate Index

Sector Health, human comfort

The UTCI is a thermal comfort indicator based on human heat balance models and designed to be applicable in all seasons and climates and for all spatial and temporal scales (Bröde et al. 2012). There are 10 UTCI thermal stress categories defined as follows:

above +46: extreme heat stress; +38 to +46: very strong heat stress; +32 to +38: strong heat stress; +26 to +32: moderate heat stress; 

+9 to +26: no thermal stress; +9 to 0: slight cold stress; 0 to -13: moderate cold stress; -13 to -27: strong cold stress; 

-27 to -40: very strong cold stress; below -40: extreme cold stress.

End User General public, health authorities Bologna
Calculation method UTCI is calculated in the Town Energy Balance (TEB) model (Masson 2000) used during the downscaling of regional climate data.
ID Title Period Statistical processing Unit Threshold Comment
UTCI sun Universal Thermal Climate Index hourly hourly oC see Description

UTCI for a person in the sun

UTCI shadow Universal Thermal Climate Index hourly hourly oC see Description

UTCI for a person in the shadow

Provenance These indicators are based on the output from the Harmonie meteorological model.
Validation The simulations made by HARMONIE-AROME in Urban SIS have been validated against observations in Urban SIS deliverable 5.1, where an overview is given in Table 4.  
Calculation caveats Spatial representation: S1
Other caveats: 
Could be compared to:
Could be used with:

The UTCI is selected for this work (in addition to the Thom Discomfort Index) because it uses a human energy balance approach to account for heat exchange between humans and the surrounding atmosphere. This physiologically-based method is also incorporated and used in operational urban climate canopy models such as TEB (Masson, 2000).

Experience user  

Bröde P et al. 2012: Deriving the operational procedure for the Universal Thermal Climate Index (UTCI). International journal of biometeorology 56:3, 481-494.

Masson V 2000: A physically-based scheme for the urban energy budget in atmospheric models. Boundary-layer meteorology 94:3, 357-397.