PARIS (AP) — A blistering heatwave gripped southwest France on Monday, sending thermometers soaring to 43 degrees Celsius (109.4 Fahrenheit) in parts of the Charente and Aude.

In Aude, a patchwork of vineyards and Mediterranean scrubland, hundreds of firefighters remained on the hillsides guarding the edges of a massive blaze that scorched 16,000 hectares last week. Officials say the flames are under control, but warn the fire will not be fully extinguished for weeks, with hot spots still smoldering.

The national weather authority, Meteo-France, placed 12 departments on red alert, France’s highest heat warning, anticipating exceptional heat stretching from the Atlantic coast to the Mediterranean plains. Forty-one other departments were under lower-level orange alerts, as was the neighboring microstate of Andorra, between France and Spain.

Social media images showed shuttered streets in Valence, residents shielding windows with foil to reflect the light, and tourists huddling under umbrellas along the Garonne in Toulouse. Across the south, café terraces stood empty as people sought cooler corners indoors.

The red alert has been issued only eight times since it was created in 2004 after a deadly summer the year before. It is reserved for extreme, prolonged heat with major health risks and the potential to disrupt daily life. The designation gives local officials powers to cancel outdoor events, close public venues and alter school or summer camp schedules.

The heatwave, France’s second of the summer, began Friday and is expected to last all week, carrying into the Aug. 15 holiday weekend. It is already pushing northward, with 38 C (100.4 F) forecast in the Centre-Val de Loire region and up to 34 C (93.2 F) in Paris.