Commuters are baring lots of skin in western Europe and authorities in countries like France are reaching out to vulnerable populations as the region sweats over unusually hot summer weather.

A mass of hot air moving north from Africa has driven up temperatures in Spain, Portugal, Britain and France in recent days. Temperatures in Paris were expected to hit 39 degrees Celsius (102 Fahrenheit) Wednesday afternoon.

Southwest France saw temperatures reaching 42 C (107 F) and Cordoba in southern Spain recorded nearly 44 C (111 F).

Paris authorities opened special air-conditioned rooms to the public and were checking on the elderly. France is particularly sensitive about the issue since thousands of people died in a heat wave in 2003.

The last time Paris saw 40 C in July was in 1947, according to Meteo France forecaster Francois Gourand. August is hotter, but 2003 was the last time Paris saw 40 C in that month.

At Paris' Gare de Lyon train station, public announcements repeatedly reminded people to drink lots of water and not overexert. A few medics were deployed in case of emergency.

"We have a lot of heat-wave days ahead of us," Gourand said, noting that a wide swath of southern France from Toulouse to Lyon was looking at temperatures of up to 41 C until the middle of next week.

British and Italian authorities were also on alert Wednesday.

In Britain, less accustomed to sweltering climes than is France, one cheeky Web site gave a "taps aff" — Scottish for "tops off" — grade to London as the mercury was forecast to hit 34 C Wednesday in a one-day heat wave.

Portugal, meanwhile, is bracing for what could be a challenging forest fire season after an exceptionally dry winter and spring, and the hottest and driest June for 12 years.

During the critical risk period, the Civil Protection Service will have its full assets on permanent standby — more than 9,700 firefighters, just over 2,000 vehicles and 45 aircraft.

Some 230 lookout towers across the country will be staffed by unemployed people.