The humidex is a Canadian innovation, first
used in 1965. It was devised by Canadian meteorologists to describe how hot,
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 stifling the air feels than
either temperature or humidity alone.
The humidex is widely used in Canada. However, extremely
high readings are rare except in the southern regions of Ontario, Manitoba and
Quebec. Generally, the humidex decreases as latitude increases. Of all Canadian
cities, Windsor, Ontario has had the highest recorded humidex measurement: 52.1
on June 20, 1953. The hot, humid air masses which cause such uncomfortable
weather usually originate in the
Gulf of Mexico or the
Caribbean.
Guide to summer
comfort
Range of humidex: Degree of comfort
Less than
29 : No discomfort
30 to
39 :
Some discomfort
40 to
45 :
Great discomfort; avoid exertion
Above
45 : Dangerous
Above
54 : Heat stroke
imminent
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.
During the dog days of summer, remember that Fido too feels
the heat. When the humidex is high, take special care to ensure that your pet is
well-protected from the heat and has plenty of water to drink.
Despite its limitations, the humidex remains a
useful, and hence popular, means of determining how hot it actually feels
outside.
Humidex
calculator>
