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Sleeping in the heat is now a health and housing problem in Barcelona
Getting a good night's sleep in Barcelona is becoming increasingly difficult, even before summer officially arrives. Tropical nights—when the minimum temperature doesn't drop below 20 ºC—have already appeared this May in the city and at the Observatori Fabra, a clear sign that nighttime heat is arriving earlier.
The difference between one night and another matters. A tropical night is when the minimum stays at 20 ºC or higher; a torrid night is when it doesn't drop below 25 ºC; and a roent night is when the minimum reaches or exceeds 30 ºC. Every summer, Barcelona experiences tropical nights, is starting to normalise torrid nights in its warmest neighbourhoods, but has not yet recorded any roent nights in the city.
The phenomenon is not evenly distributed. El Raval is often one of the areas hardest hit by nighttime heat, due to its urban density, narrow streets, and the accumulation of heat during the day. In 2024, this neighbourhood recorded the most tropical and torrid nights in both Barcelona and Catalunya, with 67 tropical and 25 torrid nights during the summer.
In extreme years, the numbers can be even harsher. In August 2023, El Raval had already accumulated 76 tropical nights and 27 torrid nights—a figure that sums up better than any feeling what it means to live in an area where the heat doesn't leave, not even at dawn.
This year, the early start is worrying because it confirms a trend: warm minimums are arriving earlier, leaving later, and turning rest into an urban problem. It's not just about being hot. Sleeping badly for several nights in a row affects mood, performance, cardiovascular health, and the ability to recover, especially for older people, children, those with chronic illnesses, and residents living in poorly ventilated flats.
The urban heat island explains part of the problem. Asphalt, façades, and buildings absorb energy during the day and release it slowly at night. In dense neighbourhoods, with little greenery and poor ventilation, the temperature takes much longer to drop than in higher or more open areas, such as Collserola or some parts of the Zona Universitària.
The sea also plays a role. When the water is warmer than usual, the early hours lose their ability to cool down. This May, the Costa Brava surpassed 20 ºC at the surface earlier than ever since records began—a sign of a Mediterranean that is accumulating heat sooner each year.
For Barcelona, tropical nights are no longer just a meteorological curiosity. They are a concrete way to measure how life in the city is changing: when the fan gets switched on, how hard it is to sleep, which homes offer better protection from the heat, and which neighbourhoods suffer most. Climate adaptation doesn't just start with big plans; it also begins with something as everyday as being able to close your eyes without your home still burning after midnight.