BACKGROUND: 2018-2020 were unusually warm years in Germany, and the summer of 2018 was the second warmest summer since record-keeping began in 1881. Higher temperatures regularly lead to increased mortality, particularly among the elderly. METHODS: We used weekly data on all-cause mortality and mean temperature from the period 1992-2021 and estimated the number of heat-related deaths in all of Germany, and in the northern, central, and southern regions of Germany, employing a generalized additive model (GAM). To characterize long-term trends, we compared the effect of heat on mortality over the decades. RESULTS: Our estimate reveals that the unusually high summer temperatures in Germany between 2018 and 2020 led to a statistically significant number of deaths in all three years. There were approximately 8700 heat-related deaths in 2018, 6900 in 2019, and 3700 in 2020. There was no statistically significant heat-related increase in deaths in 2021. A comparison of the past three decades reveals a slight overall decline in the effect of high temperatures on mortality. CONCLUSION: Although evidence suggests that there has been some adaptation to heat over the years, the data from 2018-2020 in particular show that heat events remain a significant threat to human health in Germany.