When the temperature is 30 °C (86 °F) and the dew point is 15 °C (59 °F), the humidex is 34. Note how humidex is a dimensionless number, but it indicates an approximate temperature in °C. If the temperature remains and the dew point rises to , the humidex rises to 42. The humidex tends to be higher than the U.S. heat index at equal temperature and relative humidity.