The European Union has urged member states to prepare for wildfires this summer as the continent faces another extreme weather shift that scientists say is being triggered by climate change.

In the Spanish city of Seville, one of the hottest spots in Europe this week, some unions called for workers to be sent home. Temperatures in many parts of Spain have been topping the 40 C (104 F) mark for several days and are expected to keep doing so through next week.

Seville became the first city in the world to take part in a pilot project that names and categorizes heatwaves in an effort to raise awareness of the health hazards caused by extreme heat and the precautions citizens should take.

“Climate-driven extreme heat is killing more people than any other of the climate-driven hazards. Heat is invisible, it is silent and it kills slowly, and people are not aware of it,” said Kathy Baughman McLeod, director of the Arsht-Rockefeller Resilience Center of the Atlantic Council.

Britain’s Met Office weather agency warned Friday that record temperatures expected next week pose a risk of “serious illness or danger to life.”

The office issued its first-ever “red warning” of extreme heat for Monday and Tuesday, when temperatures in southern England are forecast to reach 37 Celsius (98.6 Fahrenheit). There is a chance that temperatures could breach the highest-ever recorded in the U.K. — 38.7C (101.7F), which was set in 2019.

The Met Office weather alert, which covers a big chunk of England from London up to Manchester, warns of danger to life, disruption to air and rail travel and potential “localized loss of power and other essential services, such as water or mobile phone services.”