The humidex (short for humidity index) is an index number used by Canadian meteorologists to describe how hot the weather feels to the average person, by combining the effect of heat and humidity. The humidex is a dimensionless quantity based on the dew point, but it is equivalent to dry temperature in degrees Celsius (omitting degree symbol '°'). For example, if the temperature is , and the calculated humidex is 40, then it indicates the humid heat feels approximately like a dry temperature of .