PARIS (AP) — Joggers wheezed, electric trains stalled, and Britain sweated through its hottest July day on record as a broad swath of Western Europe sweltered in a heat wave.

Authorities in France and elsewhere, mindful that thousands died during a 2003 heat wave, reached out to the elderly, families and other vulnerable people on Wednesday to warn of health risks. Paris officials opened special air-conditioned rooms for the public.

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

France's national railway operator said the soaring heat had caused a disruption to some traffic in and out of Paris' Saint-Lazare train station. The Energy Ministry reported some overnight electricity outages and fires as a result of swooning temperatures.

Britain's Met Office, the weather forecasting service, said Wednesday was the hottest July day since records began in the 1800s based on the 36.7 C (98 F) recorded at London's Heathrow airport.

French officials said their heat wave was just beginning. On Tuesday, southwest France saw temperatures reaching 42 C (107 F) and Cordoba in southern Spain recorded nearly 44 C (111 F).

The last time Paris saw 40 C (104 F) in July was in 1947, according to Meteo France forecaster Francois Gourand. August is hotter, but 2003 was the last time Paris saw such high temperatures in that month.

At Paris' Gare de Lyon train station, public announcements repeatedly reminded people to drink lots of water and not over-exert themselves. Medics were on call in case of emergencies.

"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 facing heat of up to 41 C (105 F) until the middle of next week.

Climate is on many French minds for another reason. Paris is hosting a major international climate conference in December that will aim to curb heat-trapping greenhouse gas emissions.

In Britain, many commuters outside the London subway weren't bothered by the sweltering heat. Some responded with a classic British quip: "Mustn't complain."

"I'm loving it. I can't complain," said Maggie Cloud, a university student who planned to relax in the park. "We pay so much money to go abroad to holidays, and now we have the weather here. It's cheaper."

In Spain, tourists looking for sun and beach time didn't mind the heat either.

"Beautiful. We're coping very well," said Petroneo Zaldumbide, a 65-year-old Ecuadorean on holiday.

Spanish authorities said the past week brought record June temperatures, with Madrid recording its highest temperature in 95 years as thermometers came close to 40 C (104 F).

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

The Civil Protection Service said more than 9,700 firefighters, 2,000 vehicles and 45 aircraft would be on permanent standby this season. Some 230 fire lookout towers across the country will also be staffed by unemployed people.

___

Sylvia Hui in London, Jorge Sainz in Madrid and Angela Charlton in Paris contributed to this report.