France is bracing for a period of intense heat starting from the middle of the week, which could mark the first genuine heatwave of the year, according to Corentin Perrot, a forecaster at the national meteorological institute Météo-France. Speaking to AFP, Perrot noted that while a heat event had already occurred at the end of May, this one could be more intense, potentially meeting the official criteria for a heatwave.
In France, a heatwave is declared when the national thermal indicator (ITN), which averages daytime and night-time temperatures from 30 weather stations across the country, exceeds 23.4°C for three consecutive days, and reaches at least 25.3°C on one of those days. At the end of May, the ITN reached an unprecedented 24.8°C for that month, qualifying as a heat episode but not a full heatwave.
What makes this upcoming heat event noteworthy, according to Météo-France, is its timing: it will occur close to the summer solstice, during the longest days of the year. With shorter nights, there is less opportunity for temperatures to cool, and minimum temperatures are expected to remain unusually high. From Wednesday and Thursday, overnight lows of 18°C to 22°C are forecast, pushing the ITN even higher.
Although this period of heat will not be as early in the season as the one recorded in May, temperatures are set to rise well above seasonal averages. For example, on Thursday, Météo-France is predicting highs of up to 38°C in Nevers, 37°C in Paris and Brive, 36°C in Lyon, and 35°C in Toulouse. The duration of the hot spell will depend on the arrival of thunderstorms, which are expected to bring some relief at the end of the week.
In Luxembourg, temperatures will climb steadily from highs of 20°C to 22°C on Monday to around 30°C by Wednesday. After a mostly clear Monday, some cloud cover is expected on Tuesday, with daytime highs between 28°C and 30°C forecast for Wednesday, accompanied by light winds.
According to Meteolux, temperatures could reach as high as 33°C on Friday. While overnight lows may still drop to 7°C early in the week, nights will become much warmer from Wednesday onwards, with the mercury not falling below 19°C by Friday night. The sky will remain mostly clear or only lightly veiled throughout the period.
