You find it cold in Montréal ? trust me, it is even worse

As people say in Montréal, “aujourd’hui, il fait frette”. And I have been surprised recently when some people told my that we would reach -35°C Sunday evening… I checked around, and I found -25°C on all weather forecast websites. But nowhere -35°C. I asked some friends, and they told me that those people were not really looking at the air temperature (as we observe on the thermometer), but they were looking at the wind chill, also called “felt air temperature on exposed skin due to the wind” (température ressentie).
And indeed, such a quantity does exist, and can be found on website. There is also a physical background for that quantity. Hence, the windchill is defined as

where is the air temperature (in °C), and the wind speed (in km/h). Please don’t ask me how to interpret this power 0.16 (I already find difficult to explain a square root in an econometric equation). If we look at the past previous days we observe the following observations,
where points on top are temperature, while below we have felt temperature.So, basically, winters are even colder than what you might think..

And the story is not over, yet. The same thing holds for summer: if you take into account humidity, summer are even hotter than what you think… There is thehumidex, defined here as

where denotes a dewpoint (see here for more details).

That index appeared in the 70’s, with a work of Masterson and Richardson entitled a method of quantifying human discomfort due to excessive heat and humidity (published in 1979).By that time, in Canada, on average, 22 people died, per year, because of those excessive heat and humidity. For those interested by the origin of that index, you can have a look here.
Recently, @Annmaria (here) told me that one might expect variance to increase, i.e. maximas should be increasing faster than minimas. I just wonder if this intuition can be related to the fact that more and more people (including some medias) now talk more about felt temperatures than measured temperatures. And if we compare past temperatures to felt temperature we have today, it looks like the difference between extremes is increasing….

OpenEdition suggests that you cite this post as follows:
Arthur Charpentier (January 25, 2011). You find it cold in Montréal ? trust me, it is even worse. Freakonometrics. Retrieved July 17, 2024 from

2 thoughts on “You find it cold in Montréal ? trust me, it is even worse”

  1. Je n’ai jamais tant gelé qu’un hiver en Bretagne. Il faisait 5’C lorsque je suis partie de Brest. Arrivée à Montréal, il faisait -24’C, j’ai enlevé un chandail de laine. Mais -34’C, ressenti ou réel, c’est frette en taboire.

    Merci pour la formule de conversion.

  2. Bonjour, Il y a une faute de frappe sur le titre (it is worse je pense) Sinon article très interessant

    REPONSE: merci, je me disais bien qu’il existait une expression toute faite

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.