Two weeks ago, there was a frost advisory in place for parts of our region; today, some are finding the heat intolerable.   Pretty quick turnaround!  While most people complain about the cold all winter, not everyone is a fan of this high heat and humidity.  This afternoon, the feel-like temperature will come close to 35 in many communities away from the water.

That feel-like temperature is not an actual temperature.  It’s not measured, it’s calculated, so it’s a value.  Many people struggle with the concept of humidex.  The problem is there is no objective way to put a number on what something "feels- like". therefore an arbitrary base had to be chosen.  So, the humidex is a measure of what temperature it would feel like based on a dew point of 7 degrees Celsius. The current formula for determining the humidex was developed by J.M. Masterton and F.A. Richardson of Canada's Atmospheric Environment Service in 1979.

To complicate matters, you might have heard the term Heat Index used during weather broadcasts south of the border.  The heat index uses a dew point base of 14 °C.  The heat index was developed in 1978 by George Winterling as the "humiture" and was adopted by the USA's National Weather Service a year later.

According to the Meteorological Service of Canada, a humidex of  30 or more causes "some discomfort", 40 causes "great discomfort" and above 45 is "dangerous". When the humidex hits 54, heat stroke is imminent.

The record humidex in Canada occurred on July 25, 2007, when Carman, Manitoba hit 53.0 !       

Some of you might be happy to hear that we can expect quite a dip in those high humidex values tomorrow afternoon behind an advancing cold front.  Some will complain about how cool it is Saturday morning, but I’ve come to accept the fact that that’s how it is in this business!


Chief Meteorologist

Cindy Day