As a general rule, the heating is turned on between 5 and 20 October and turned off around 15 April. This varies depending on the region, your accommodation and, most importantly, the weather. With climate change, if we notice that the heating has been turned on frequently after October 15 in the last two decades, it also happens that the first periods of great coolness encourage to re-ignite it promptly in September. This may have been the case in 2017, which was the coldest September in recent years, and during which the thermal indicator dropped to 16.43 ° C, which is over 1.5 ° C below average. . Compared to September 2021, which had been the hottest with an indicator of 21.45 ° C, the concept of extreme climate variability takes on its full meaning.
Unified Graduation Days Reminder (DJU)
The degree day is a value representative of the difference between the average temperature of a day (which is obtained by adding the minimum and maximum temperature and then dividing the result by two) and a pre-established temperature threshold (17 ° C). Added over a period, the DJU calculate the heating or cooling needs of a building. These data are calculated every day to establish monthly but also annual averages during the “heating season”, which by convention extends from January to May and from October to December. These results are then compared with the statistics of the period 1991-2020, to define an index of rigor.
If this index is greater than 1, it means that the period considered was more rigorous than the average. Otherwise it would have been less rigorous. Thus, since 2013, only 3 years have been more rigid: 2013, 2016 and 2021 (which had been characterized by severe frosts in April, by the coldest month of May since 2000, and by several episodes of cold from January to March and by November to December).
The month of September is not included in these calculations, but it still happens, as in 2017, that periods of cold are observed. This was particularly the case in the period from 15 to 20, when temperatures were particularly cool and on average 3 to 4 ° C lower than normal. These cool periods are therefore not uncommon in September, as will be the case from next weekend. So what to expect in the next few days?
A burst of lasting freshness
It is recommended to turn on the heating when the internal temperature drops below 19 ° C for several consecutive days and the thermal indicator (average external temperature) reaches 17 ° C. The thermal indicator calculated by our services will drop to 13.9 ° C from this Saturday and will remain between 2 and 3 ° C below the norm at least until Friday 23 September, the situation will therefore be favorable to recovery en route from your boiler .
It is explained by the establishment, at high altitude, of a cold current of polar origin that precedes a flow coming from the east continental. This development will lead to a general drop in temperatures during the night and in the morning. Thanks to the sun, much more present in the south than in the north, the decline will still be contained in the afternoon. Your sensation will even become pleasant, with temperatures around the norm. The nights and mornings will therefore be cool and locally cold from Saturday, with values from 4 to 7 ° C near the Massif Central, and from 7 to 14 ° C from north-east to south-west. This drop will increase on Sunday morning, especially in the Southwest, where you will lose 6 ° C in 24 hours. A risk of white frosts will therefore be possible near the Massif Central. This general pattern will persist throughout the week.
Credit: The Weather Channel
The reliability of this change in the weather model is very high. It is less so in the detail of each day, due to doubts about the more or less significant presence of clouds in the north, and the risks of fogs and mists in the southwest.
How to reduce consumption by heating less?
In the context of the energy crisis we are experiencing, the hunt for expenses is on. And there are some simple reflexes to adopt to maintain the temperature of your interior without turning on the heating, or limiting it: securely close windows, doors and shutters at night. On the contrary, as soon as the sun comes out, bring it inside by opening shutters and curtains during the afternoon. If you heat, be sure to adjust the temperature according to your rooms: 19 ° C during the day for the living room and kitchen and 17 ° C in the bedrooms. At night, or when you are away from home, you can lower the temperatures in the living room and kitchen by 3 ° C.
The thermal amplitudes will be strong between the cold in the morning and the very pleasant sensation with the afternoon sun. It will therefore be important to dress well to protect your health. It is then time to pull out the sweaters for the cooler hours and try the famous onion technique: for the coldest and coldest of you, this technique involves cleverly wearing multiple layers of clothing in cold weather, so remove them as temperatures rise, all without making you cry!