4th summer heat wave next week – La Chaîne Météo

By Regis CREPET, meteorologist
Published on 08/04/22, updated on 08/06/22 at 6:00 p.m. A new heat wave is inevitable next week in France. It will start Monday from the south before reaching the west and the center and then the whole territory from Thursday until the weekend of August 15. While the current heat wave is regressing this weekend in our country, the hot summer weather is not over yet. On the contrary, the very hot air present on the Mediterranean will go up on France from the beginning of next week, to progress towards the north. This new heat wave is likely to be long-lasting. If holidaymakers appreciate, for some, this type of weather, this situation will lead to a 4th heat wave and will especially accentuate the drought. A stubborn anticyclonic blockage If the current summer seems endless with its repeated scorching days and exceptional drought, it is because of the persistence of high pressures over Western Europe. These anticyclones prevent the disturbances from passing over our country and slow down the stormy evolution. Oscillating between Ireland and Germany, these high pressures influence the direction of the winds: when they turn to the northeast, it lowers the temperatures a little, then when it turns to the south, the heat intensifies. This process has been repeated tirelessly since July 1st. It should be noted that these changes in air masses occur without a thunderstorm, which increases the dryness. A “heat pump” off Portugal Alongside these anticyclones, “small” isolated depressions on the Atlantic, off Portugal, act as “heat pumps”, i.e. in turning anti-clockwise, they cause puffs of hot air to rise from Morocco to France, with intense heat strokes that have raised the temperature to 40°C in Britain for example. The combination of these parameters (anticyclones and heat pumps) is one of the main characteristics of this summer of 2022. A 4th heat wave next week In the context that we have just described, a powerful anticyclone will be present over the British Isles in beginning of the week. Then, small depressions will form off Portugal, the precise location of which will remain to be determined. This situation will be favorable to the rise of warm air over the whole of France, from the south, and gradually gaining towards the north. Thus, it is assumed that a warm period will set in on Monday, then increase in intensity until next weekend. A heat wave is characterized by a national thermal indicator (average daily temperatures across the country) that exceeds 25.3°C, then does not drop below 23.4°C. This will be the case again on Monday, with a maximum expected between 25 and 26°C for the second half of the week. Insured risk of a heat wave A heat wave is a heat wave in XXL format, i.e. which reaches predefined temperature thresholds (generally around 20°C at night and 36°C during the day), for at least 3 days and 3 nights in a row. For next week, the risk of reaching these thresholds depending on the duration of the heat wave is now 100% insured. The more durable it is, the more the heat will increase. This perspective is acquired from the middle of next week in all regions south of the Loire. The regions north of the Loire could experience less intense heat due to the persistence of a light north-easterly wind. To date, there are two possible weather scenarios. The majority scenario envisages a heat wave from Monday to next weekend inclusive. The second scenario could allow us to escape it, with a heat wave that would be cut short by the arrival of cooler ocean air from the northwest. This scenario is now in the minority. In both cases, France will not avoid strong heat. Holidaymakers will certainly be able to appreciate this persistent good weather, but the duration of such temperatures constitutes a public health problem. Moreover, without rain and with the persistent east wind, the drying out of the soil and vegetation will be even more pronounced. The risk of vegetation fires will once again be present due to the northeast wind and the extremely dry soil. Read also Weekend weather: less sun and heat in the north, stormy in the south July 2022 weather report: record drought and sunshine