Germany's June heatwave kills estimated 5,100, deadliest week in 26 years

Death toll estimates

Germany's mid-June heatwave has led to an estimated 5,100 heat-related deaths, according to the Robert Koch Institute (RKI). The figure already exceeds the average annual heat death toll of 2,900 for the years 2023 to 2025. The RKI's model suggests that 4,310 of those deaths occurred in the week of 22 to 28 June, when temperatures soared.

Record mortality

Preliminary data from the Federal Statistical Office (Destatis) shows that 23,665 people died in Germany during that same week, a 28% increase from the previous week and 47% above the 25-year average. That makes it the deadliest summer week since at least the year 2000, surpassing even the severe heatwaves of 2022, 2018 and 2015. The RKI notes that its own estimate of heat-related deaths may understate the true impact, as Destatis recorded an excess mortality of 6,800 cases that week, though the calculation methods differ.

Who is most at risk

The elderly bore the brunt of the heat. The RKI estimates that around 2,950 of the victims were aged 85 or older, with a further 1,320 aged 75 to 84. Among those 65 to 74, an estimated 550 died, and about 300 were under 65. The institute explains that heat rarely appears as a cause on death certificates.

In some cases, such as heat stroke, heat exposure leads directly to death, while in most cases the combination of heat exposure and pre-existing conditions leads to death.

A hotter baseline

The nationwide average weekly temperature for 22 to 28 June was 26.4°C, far above the 20°C threshold at which the RKI expects a significant rise in mortality. Record temperatures of up to 40°C and a series of tropical nights placed vulnerable groups under extreme strain.

Year-on-year comparison

The 5,100 heat deaths recorded by late June dwarf the figures for the same period in previous years. The RKI counted 560 heat-related deaths in April to 28 June 2025, 470 in 2024, and 810 in 2023. The institute attributes the stark difference to the intensity and duration of this year's heatwave.