Deadly heat in Europe means tourists and residents alike are advised to stay inside during this peak travel season.

In Italy, Spain, and Greece, the second extreme heat wave in July is hitting, combining with expansive wildfires to make for a hellish tourist season. This deadly heat wave is expected to persist for days, and might break the all-time high temperature for southern Europe (119.8F, set in Sicily in 2021).

“Heat waves are really an invisible killer,” Panu Saaristo, the emergency health team leader for the International Federation of Red Cross and Red Crescent Societies, said during a Geneva briefing. “We are experiencing hotter and hotter temperatures for longer stretches of time every single summer here in Europe.”

Cyprus reported one death and six hospitalizations from heatstroke over the weekend, when daytime temperatures rose above 110F. In Rome, volunteers are handing out water bottles and encouraging frequent water drinking among the city’s thousands of tourists.

The extreme weather events, including dozens of neat hottest-temp records set this summer, are all due to the combination of human-caused climate change from fossil fuels, and this year’s El Nino weather pattern, which won’t peak until winter.

Last year, over 61,000 heat-related deaths happened in Europe, mostly in the tourist hot spots in southern Europe. Travelers are encouraged by officials to take caution, and to schedule outdoor excursions in the earliest, coolest parts of the day. In some destinations like Greece, major outdoor sites like the Acropolis are being closed during afternoon hours to protect workers and tourists.

Some countries like France have a warning system about deadly temperatures, and travelers should acquaint themselves with it. They should also keep abreast of air quality information, and local wildfire warnings.

It’s also advised to be patient with locals. Vacationers are, no matter their intention, contributing to the problem, especially those who arrive by air travel or cruise ship. Even in local economies dependent on tourism dollars, it’s hard not to feel that.