Europe braces for 104-degree heat as experts warn 'tropical nights' may be the bigger threat

Europe is heating up once again, with parts of the continent expected to approach 104 degrees Fahrenheit just weeks after a deadly early-summer heat wave.

However, experts say the greater danger may come after dark, as so-called "tropical nights" keep temperatures from falling enough for the body to recover.

What's happening?

Another wave of high temperatures is taking shape over southern and central Europe in the coming days, with Spain, Portugal, France, and Italy all in its path. As Euronews reported, Seville, Zaragoza, and Córdoba could all approach 100 degrees Fahrenheit, while Spain's weather agency, AEMET, has issued yellow heat warnings in parts of the country.

Temperatures near 100 degrees are forecast in southwestern France and around Bordeaux, where officials are again preparing for dangerous heat after several deaths during last month's heat wave. Inland Portugal could also see temperatures reach triple digits or higher, meteorologist Maria João Frada warned.

"We are already talking about temperatures of around 35 to 40 degrees Celsius by the start of next week," Frada said, according to the June 17 report.

Ionna Vergini, founder of wyf24, said the current pattern is more than a typical stretch of summer warmth. "This isn't just another hot week; it has the structural fingerprints of an atmospheric blocking event, not a passing warm spell," Vergini told Euronews Earth.

Why does it matter?

Euronews pointed to the return of "tropical nights" as one of the main concerns, using the term to refer to periods when temperatures remain above 68 degrees for 24 hours.

That means little to no overnight relief, especially in cities where concrete and asphalt absorb heat during the day and release it after sunset. Vergini warned that nighttime heat may be even more dangerous than the daytime peak.

"Sustained nighttime heat is arguably a greater public health threat than the daytime peak," she said. "When lows fail to drop below 20 degrees Celsius (68 degrees Fahrenheit) and in the worst cases stay above 25 degrees Celsius (77 degrees Fahrenheit)  ... the body is denied its vital recovery window, and the cardiovascular system stays under constant strain to cool the core." 

Vergini added: "Excess mortality during heat waves correlates much more heavily with consecutive high nighttime minimums than with a single hot afternoon."

Worsening extreme weather disasters put lives and livelihoods at risk by increasing heat illness, worsening sleep, straining hospitals, and disrupting work, school, and transportation. They also threaten economic stability when electrical grids buckle under air-conditioning demand, trains are delayed, and cities must spend more to respond to emergencies and repair damaged infrastructure.

Turin experienced major blackouts during May's heat, while France's Transilien rail network has urged riders to check schedules because extreme temperatures can interfere with service.

What can I do?

Keeping bedrooms as cool and dark as possible, staying hydrated through the evening, and checking on older adults, children, and neighbors without access to cooling can all make a meaningful difference.

It can also help to shift errands, exercise, and outdoor work to the early morning, since back-to-back hot days and hot nights can cause stress to build over time. Some schools are even considering schedule changes because students are struggling to sleep in the heat.

Cities and households can reduce the danger through shade, tree cover, reflective surfaces, and home weatherization that helps keep indoor temperatures safer.

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