Europe saw the second-highest number of tropical nights on record in 2024 due to climate change, according to the EU’s Copernicus service (C3S).
A tropical night is defined as a night when the temperature does not drop below 20C.
Over the past few decades, the number of tropical nights in Europe has been rising. The rate of warming is more than double the global average over the last 30 years.
The southeast of Europe was particularly affected, with some areas of southern Greece experiencing up to 55 more tropical nights than average.
Much of Italy saw up to 50 additional tropical nights, while western Turkey recorded up to 40 more.
Some regions in Croatia, Serbia, Hungary, Romania, and Bulgaria experienced up to 35 extra tropical nights.
In June and early July of 2025, many areas across the European continent experienced more tropical nights than usual for that period.
Parts of Spain, for example, recorded up to 24 tropical nights in June, which is 18 more than the average for that month.
Linked to the marine heatwave in the Mediterranean Sea, coastal areas around the Mediterranean Sea saw around 10 to 15 tropical nights, despite typically not experiencing any in June.
A World Weather Attribution study has also found that Sweden endured 10 consecutive tropical nights due to a prolonged Nordic heatwave.
“Nighttime temperatures have been made about 2C hotter than they would have been without human-caused climate change, and around 33 times more likely,” the report stated.
“After a further 1.3C of warming, nighttime temperatures are projected to warm by a further 1.7C, with temperatures like those recorded in 2025 a further seven times more likely to occur. “
How do tropical nights affect your health?
Tropical nights might mean a sleepless, sweaty time in bed, when bed sheets cling to skin and opening windows brings no respite.
Besides being uncomfortable, high nighttime temperatures can pose health risks, as the body may not recover from daytime heat stress as it normally would.
Symptoms of heat stress include increased heart rate, dizziness, and, in severe cases, heat stroke.
There were estimated to be around 47,700 heat-related deaths in Europe in 2023, and around 61,700 in 2022.