Italy is in its fourth heatwave of the summer, with health authorities issuing red alerts for a record 25 cities.

The alert

Italy’s health ministry issued red alerts for a record 25 cities as the country entered its fourth heatwave of the summer, Anadolu Agency reported.

What a red alert actually means

Italy uses a three-level system. Green means normal conditions. Yellow signals heat that may affect vulnerable people. Red — the top level — means the heat is dangerous for the whole population, not only for the elderly or the ill. That distinction is the point: at red level, healthy adults working or exercising outdoors are also at real risk.

Why heat is deadlier than it looks

Heatwaves rarely produce dramatic footage, which is part of why they are underestimated. But sustained high temperatures — especially when nights stay warm and the body never gets to cool down — strain the heart and kidneys, worsen existing illnesses, and cause deaths that appear in the statistics weeks later, often attributed to other causes.

Related: Europe’s heatwave is raising wartime wrecks — and squeezing power plants.

If you are travelling south this summer

Italian cities publish daily alert levels city by city, so it is worth checking the level for the specific place you are visiting rather than assuming the whole country is the same. Standard advice during red alerts: stay indoors in the hottest hours, drink water before you feel thirsty, and check on elderly neighbours or relatives who live alone.

Source: Anadolu Agency, as collected by Wikipedia’s current events portal.