Scores of people were evacuated from homes and vacation spots in Tuscany because of fires, while in Portugal, emergency crews found a couple dead in a charred forest, the national news agency Lusa reported.
The discovery of the man and woman near Braganca, 190 miles northeast of Lisbon, raised the death toll from fires that have raged for more than a week in central Portugal to 14.
Most of Portugal's fires were brought under control late Tuesday but exhausted fire crews were fighting four blazes Wednesday morning. Officials said they were concerned that expected temperatures of more than 104 degrees and strong winds would spark new outbreaks.
In southern Spain, officials said two people died Tuesday of heat stroke, raising to six the number of deaths in a single day and 14 overall. Most of the deaths were elderly people.
More hot weather was forecast Wednesday in Spain's Andalusia and Extremadura regions, with maximums of 106 degrees. Forest fires continued to burn in Extremadura and elsewhere in Spain. Some 200 villagers in northern Burgos province were evacuated overnight because of a fire set Sunday from lightning.
It was cooler in Madrid, where rain on Tuesday night brought much-wanted relief after days of sweltering temperatures.
Londoners experienced the hottest day in the city's history Wednesday, as the temperature hit 95.7 degrees, beating the 95-degree record in August 1990.
French meteorologists said this summer is the hottest since 1947, based informally on the number and duration of hot spells and the frequency of record high temperatures.
Records were set in a number of French cities on Tuesday, notably in central Tours and the northwestern city of Rennes, where it was 102 degrees. Paris temperatures hit 100, setting a new record for August, according to France's national weather service.
The mercury also hit its highest level in Switzerland, according to the private weather agency Meteomedia, which logged a temperature of 104.5 degrees in the northern Swiss village of Moehlin on Tuesday.
That would beat the previous high of 102 degrees set on July 2, 1952, in the northern city of Basel, although it was not considered an official record because it was not registered by MeteoSuisse, the government weather agency.
In most of Italy, temperatures were well into the 90s, although Florence saw 104 degrees. Italy's worst fires were on the island of Elba, off the Tuscan coast, and in the Versilia area north of Pisa, according to the civil defense department.
Tourists were evacuated as a precaution from two holiday homes on the island, while about 10 homes were evacuated in Versilia.
No injuries were reported in the fires, which broke out Tuesday night, said civil defense spokesman Luca Spoletini. Using water-spraying planes and helicopters, dozens of firefighters were struggling to put out the flames.
Other blazes erupted in the northwestern region of Liguria and in Campania, in southern Italy. Some 16 fires were raging in Italy, the spokesman said.
Greek firefighters, aided by aircraft, also fought a forest fire Wednesday on Salamis, a tiny island in the Saronic Gulf near Athens. They were hoping to contain the fire before it reached residential areas, but strong gales hampered their efforts.