A late-summer heatwave intensified across Western Europe on Monday, with Météo-France placing 12 departments under its highest red alert for heat, a figure it expects to climb to 16 on Tuesday. Temperatures surpassed 40 °C in the southwest and could reach 43 °C locally, while the capital is bracing for 36 °C. The French health ministry re-activated its toll-free advice line and reminded employers of a decree obliging them to provide at least three litres of drinking water per employee each day. Across the Channel, the UK Met Office issued yellow and amber heat-health alerts covering most of England, warning that southern counties could touch 34 °C by mid-week. Meteorologists in both countries attribute the episode to a dome of exceptionally hot air linked to a decaying tropical system, noting that climate change is making such events longer and more frequent. The extreme heat has helped to ignite and spread wildfires on both sides of the Atlantic. In Spain, authorities said about 1,400 residents have been evacuated from villages in León and elsewhere after 13 blazes erupted amid temperatures forecast to top 42 °C. Around the UNESCO-listed Las Médulas park, firefighters reported dangerous “fire-whirl” columns that forced them to pull back and destroyed several buildings. In the United States, the Lee Fire in western Colorado grew to 113,378 acres—now the state’s sixth-largest on record—and remained only 7 % contained. All 179 inmates at the nearby Rifle Correctional Center were transferred as more than 1,000 personnel worked to hold the flames west of State Route 13. Farther west, California’s Gifford Fire expanded to roughly 180 square miles; more than 3,000 firefighters are on the line during what officials call peak fire season. Public-health officials across the affected regions urged residents to stay indoors during the hottest hours, remain hydrated and check on vulnerable neighbours, warning that heat-related illnesses can escalate rapidly under the current conditions.