Thirty-Three

Another sunny, warm day awaits Luxembourg on Sunday, with scattered clouds and the mildest of breezes. Temperatures will start off at 18-20°C in the morning, rise to highs of 31-33°C in the afternoon, and remain warm at 28-30°C in the evening.[1]

Police have announced traffic checks for the day. The heat continues the pattern of the past week, with the fourth heatwave of the summer having arrived earlier this week. The Upper Sûre Lake fire ban remains in effect across four municipalities, and the Weiswampach upper lake stays closed due to blue-green algae. The water is warm, the air is warm, and the reservoirs are under stress.[2]

33°C is not a record for Luxembourg. The all-time high of 40.8°C was set in Steinsel in July 2019. But 33°C on a Sunday in August means the lakes and swimming pools will be crowded, the roads to France and Germany will be busy with holiday traffic, and the fire risk in the forests around the Upper Sûre will remain elevated. The evening temperature of 28-30°C means there is little relief after sunset. The body does not recover from the heat overnight when the air stays warm. This is the pattern that kills vulnerable people, and it is the pattern that climate scientists have been warning about for decades: not the single record day, but the sequence of warm nights and hot days that wears down the body's ability to regulate temperature.[3]