a tool to calculate the approximate humidex value
Current humidex for downtown Vienna (2018-08-20 13:39):
NaN (at 30.0°C and 0.0%RH) - Heat stroke imminent
The humidex is a dimensionless index indicating the physiological reaction to heat, taking into account the additional effect of humidity; although it is calibrated to the Celsius scale (here), it is not an absolute measure.
Sources: Wikipedia: Humidex, Environment Canada.