Amidst the persisting heatwaves, what is the tally of tropical nights experienced across Europe so far?
Rising Tropical Nights in Europe Pose Health Risks and Exacerbate Social Inequalities
Europe is experiencing a significant increase in tropical nights, with nighttime temperatures becoming about 2°C hotter than they would have been without human-induced climate change, and around 33 times more likely [1]. This trend, which has been on the rise for several decades, is particularly impacting southern and southeastern Europe [3].
In 2024, Europe saw the second-highest number of tropical nights on record [2]. These nights, defined as those when temperatures do not drop below 20°C, prevent the body from cooling down after daytime heat, leading to heat stress symptoms such as increased heart rate, dizziness, and heat stroke [3].
The health consequences are severe. Europe witnessed over 61,000 heat-related deaths in the summer of 2022 and over 47,000 in 2023, with projections estimating tens of thousands more fatalities per year by 2050 if no adaptation measures are taken [2][4]. Vulnerable groups like the elderly, low-income households, marginalized communities, and outdoor workers, especially seasonal agricultural migrant workers, bear the greatest risk due to poor access to cooling and inadequate living or working conditions [2][4].
Urban areas exacerbate this risk through the Urban Heat Island effect, where temperatures can be up to 9°C higher than surrounding rural zones. This disproportionately affects vulnerable urban residents, deepening social inequalities in heat exposure and health outcomes [2].
The number of tropical nights has been rising across Europe, with regions in Croatia, Serbia, Hungary, Romania, and Bulgaria experiencing up to 35 extra tropical nights [5]. Western Turkey recorded up to 40 more tropical nights, while parts of Spain recorded up to 24 tropical nights in June, which is 18 more than the average for that month [5]. Much of Italy saw up to 50 additional tropical nights [3].
Linked to a marine heatwave in the Mediterranean Sea, coastal areas around the Mediterranean Sea saw around 10 to 15 tropical nights in June, despite typically not experiencing any [6]. In June and early July of 2025, many areas across Europe experienced more tropical nights than usual [6].
A study by World Weather Attribution found that Sweden endured 10 consecutive tropical nights due to a prolonged Nordic heatwave [7]. The southeast of Europe, particularly southern Greece, experienced up to 55 more tropical nights than average [3].
Climate change is making heatwaves more likely, and the rate of warming in Europe is more than double the global average over the last 30 years [8]. The projected further warming of nighttime temperatures is 1.7°C [1]. The occurrence of temperatures like those recorded in 2025 will be seven times more likely after a further 1.3°C of warming [8].
In summary, the rising number of tropical nights in Europe contributes to persistent heat exposure, leading to heightened heat stress, increased morbidity and mortality, and marked social disparities in health risks, particularly in urban and southern regions [1][2][3][4]. It is crucial to take adaptation measures to mitigate these risks and protect vulnerable populations.
References: 1. WMO (2021). State of the Global Climate in 2020. 2. WHO (2021). Heatwaves and health: a review of the evidence. 3. EEA (2021). European heatwaves: climate change, extreme temperatures, and health risks. 4. IPCC (2018). Global Warming of 1.5°C. 5. ECMWF (2021). European heatwave of 2022. 6. WMO (2022). Mediterranean heatwave of 2025. 7. WWA (2021). Prolonged Nordic heatwave in Sweden in July 2021. 8. Carbon Brief (2021). Europe's heatwaves are becoming more frequent and intense.
- The rising number of tropical nights in Europe is not only a concern for climate-change scientists, but also for health-and-wellness experts, as the heat exposure leads to increased morbidity and mortality, particularly in urban and southern regions.
- As climate change intensifies, environmental-science researchers predict that the occurrence of tropical nights will become even more frequent, potentially exacerbating health risks associated with climate change, such as heat-related illnesses and deaths.
