20 August 2009

La Canicule — Dog Days

French Wikipedia defines the term « canicule » the way I heard one of the weather forecasters explain it on the France2 TV news earlier this week:
« ...on considère qu'il y a canicule quand, dans un secteur donné, la température reste élevée et l'amplitude thermique faible. Cela correspond grosso modo à une température qui ne descend pas en dessous de 18°C pour le nord de la France et 20°C pour le sud la nuit, et atteint ou dépasse 30°C pour le nord et 35°C pour le sud le jour, ceci d'autant plus que le phénomène dure plusieurs jours, et a fortiori plusieurs semaines, la chaleur s'accumulant plus vite qu'elle ne s'évacue par convection ou rayonnement. »
Plums ripening on a tree out back.
Picture taken at about 7:30 a.m. today.

That says that in France:
"The term dog days describes a period of time, in a specific area, when temperatures remain high and there isn't much thermal variation between day and night. That means, in approximate terms, nighttime temperatures that stay above 65ºF in the north or 68ºF in the south, and daytime temperatures in excess of 86ºF in the north and 95ºF in the south, lasting at a minimum for several days or, especially, several weeks, with heat building up faster than it can dissipate by convection or radiation."
The grapes are ripening fast now.

As CHM pointed out in a comment yesterday:
Canicula is the Latin name of the Dog Star, Sirius, in the Canis Major constellation. Sirius rises and sets at the same time as the Sun from July 22 to August 23. It usually is a period of great heat, that's why it is called canicule, as well as dog days for the same reason.
The forecast for this afternoon. The numbers are
wind speeds in kph. Saint-Aignan is under the
red arrow right in the middle of the map.

So there you have it. Those so-called high temperatures — lows of 65ºF and highs of 86ºF in northern France, which would include Saint-Aignan and Paris — might not seem very high if you live in the American South, on the East Coast, or in much of the American Southwest. And there is nowhere near the humidity that you get in places like Washington DC or all the U.S. Southeast.

Today's predicted highs: 30ºC in Saint-Aignan. That's 86ºF.
Now 38, in Lyon & Grenoble, is hot. That's just over 100.

It's all cultural. It's the way houses in France are built. It's the fact that home air-conditioning is nearly non-existent. I say that knowing that many people in France are equipping their homes with different kinds of roll-about or wall-mounted air-conditioning units. I think that's a mistake for the environment, but who am I to judge?

In northern France, at least, despite the exceptional hot spell that comes along every few decades (1947, 1976, and 2003, for example), there just isn't enough hot weather to justify the investment in air-conditioning. And central air conditioning is not practical because almost no houses have forced-air heating systems that can be adapted to accommodate air-conditioning.

A stand of black-eyed susans in the neighbors' garden

Cast-iron radiators don't really make good air-conditioning units. French windows, which open into the house like doors, don't lend themselves to the installation of window-unit AC.

Our temperature hit 33ºC yesterday afternoon — just over 91ºF. It wasn't unpleasant at all, but I admit that I was "glowing" when I got back from the walk with Callie at about 7:00 p.m. The low this morning was about 70ºF. It feels pleasant right now and it's supposed to cool off later today, with some rain coming in.


  1. I'm looking forward to the little storm that will break this temperature. We've got the mild winds already.

    I couldn't sleep last night, it was so hot.

    Tomorrow should be much nicer, and cooler.

  2. It always makes me smile to read about the favorite national pastime "the weather". C'est l'ete! C'est normal qu'il fasse chaud!

  3. Dedene, it has already cooled down.

    Et puis, Nadège, qu'est-ce qu'on fait quand il fait chaud à L.A. On met la clime ? :^)

  4. Ken

    Is geothermal tech expensive in France? Here I would put it if I were to build a new house but it will cost a lot if I want to replace my heat pump.

  5. Dog days here are defined by the excessive amount of time the poodles spend napping in front of the fans. 65 degrees F now at 8am, it got up to 90 degrees F yesterday

  6. Hi Ken, I’ve seen that TV weather program too and found it very enlightening. I didn’t know 'heat wave' had to do with the difference between day and night time temperatures. Television can be educational … sometimes :) Martine

    P.S. 33°C in Brussels today ... but only 20° or so in our office building!

  7. Oui Ken, when it is too hot in LA, particularly in the valleys, people have to have an air conditionner. I don't have one because I live close to the ocean. But I do have a fan. When I lived in Burbank, sometimes it was so hot, you couldn't even leave a dog outside. When the Santa Ana winds blow, it gets really bad. But I have to say that in general, every summer for about 3 weeks, we get monsoon weather coming up from Mexico. Heat and humidity is a very bad combination for me. Dry heat is much easier to take and also, we are used to it. I always feel sorry for people who have to work outside during a heat wave. Now, 110 degrees is hot and we are lucky we don't get these too often. Last year, it went up to 120 degrees for few days. I was working on a TV show, shooting outside on location.
    Every time I call my parents, they have to mention the weather (hot, cool, rainy, foggy... It definitively has an effect on moods). In Los Angeles the weather is always even but when we get one drop of rain, we are on "storm watch". I wonder if the weather topic is the same in other countries.

  8. I really enjoyed learning the common background of "canicule" and "dog days". Makes so much sense.
    The little storm hit Nogent sur Marne this afternoon -- just enough for me to make the rounds to shut the windows and then again to open up immediately. Not enough to matter. But we do have a breeze, now.
    I remember '76 and '03 very well - the "impôt secheresse", government mishandling...This is nothing like that. (Ken, you went back and forth before settling here. I've been living here since '72.)


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