Canadian Humidex Calculator This calculator requires the use of Javascript enabled and capable browsers. The humidex, devised by Canadian meteorologists, was first used in 1965 in Canada before anywhere in the world. The purpose was to create an easily understood method of describing how very hot and humid weather feels to the average person. The humidex combines the temperature and humidity into one number to reflect the perceived temperature. Because it takes into account the two most important factors that affect summer comfort, it can be a better measure of how uncomfortable the air feels than either temperature or humidity alone. The humidex is similar to the heat index but is widely used in Canada where the heat index is not. It equals H = T + (0.5555 * (e - 10)), where T is the temperature in Celsius and e is the vapor pressure in millibars (mb). This is the Canadian formula but there are variations of humidex throughout the world, of both the exact formulae and of interpretation of the results. You may enter the temperature in either scale though the actual calculation is done in degrees Celcius. We also do a conversion for you of the Celcius temperature to Fahrenheit by way of the formula, Tf = (9/5)*Tc+32.



Range of humidex: Degree of comfort or discomfort



Less than 29 : Little or no discomfort

30 to 34 : Noticeable discomfort

35 to 39 : Evident discomfort

40 to 45 : Intense discomfort; avoid exertion

Above 45 : Dangerous discomfort

Above 54 : Heat stroke probable



An extremely high humidex reading can be defined as one that is over 40. In such conditions, all unnecessary activity should be curtailed. If the reading is in the mid to high 30s, then certain types of outdoor exercise should be toned down or modified, depending on the age and health of the individual, physical shape, the type of clothes worn, and other weather conditions.



If working outdoors is an absolute necessity, drink plenty of liquids and take frequent rest breaks. In hot, humid conditions, there is a considerable risk of heat stroke and sun stroke.



Despite its limitations, the humidex remains a useful means of determining how hot it actually feels outside.



Canadian Humidex Calculator Temperature In Degrees C F Relative Humidity In Percent %

Humidex Factor In Celsius Degrees Humidex Factor In Fahrenheit Degrees Updated:8/13/11