The UTCI is a thermal comfort indicator which can assess outdoor thermal conditions and provide good predictions of thermal sensation votes depending on outdoor meteorological conditions.

You can calculate the UTCI of any location using the actual values of air temperature (Ta), mean radiant temperature (MRT), wind speed (va) and relative humidity, expressed as water vapour pressure (hPa).

To calculate for MRT using globe temperature:

To calculate for water vapour pressure using RH:

Use the mean radiant temperature, water vapour pressure, air temperature and wind speed as inputs in the UTCI calculator.

Your calculated UTCI equivalent temperatures can be expressed in terms of thermal stress using the stress categories as shown on accompanying table:

UTCI calculator

References:

[1] Bröde, P., Fiala, D., Błażejczyk, K., Holmér, I., Jendritzky, G., Kampmann, B.. et al. (2012). Deriving the operational procedure for the Universal Thermal Climate Index (UTCI). International Journal of Biometeorology, 56(3), 481-494.

[2] Bröde, P., Krüger, E., Rossi, F., & Fiala, D. (2012). Predicting urban outdoor thermal comfort by the Universal Thermal Climate Index UTCI —a case study in Southern Brazil. International Journal of Biometeorology, 56(3), 471-480.

[3] ISO. (1998). ISO 7726:1998 Ergonomics of the thermal environment — Instruments for measuring physical quantities (pp. 51). Geneva: International Standards Organisation (ISO).

[4] Vaisala (2013). Humidity Conversion Formulas – Calculation formulas for humidity. Helsinski, Finland (pp. 17).

[5] www.utci.org