The mercury was expected to climb to 45 C in some parts of Portugal on Sunday, but would not go above the 46.8 C recorded the day before in Alvega, 150 kilometres (93 miles) north of Lisbon, the Portuguese Institute for Sea and Atmosphere (IPMA) said.
In Spain, authorities issued heat warnings for 41 of the country's 50 provinces as temperatures reached up to 44 degrees.
Meteorologists say temperatures are being driven higher by a hot air mass moving northward from Africa, which is also bringing dust from the Sahara Desert.
And as we move into the weekend the mercury will remain high, as blisteringly hot weather sweeps in from Spain and Portugal.
Britain's long, hot summer has taken its toll on the country's flowers.
Portugal's Civil Protection Agency has been sending mobile text alerts warning of extreme fire risk in some areas, as they seek to avert casualties.
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The torrid weather has been felt across Europe, as far north as Sweden and Britain, whose weather service said July was the country's third-warmest month in more than a century.
A Europe-wide heatwave in recent weeks has seen drought and wildfires across the continent.
Europe's weather warning group, Meteoalarm, has already issued red warnings - categorised as very risky and posing a risk to life - for much of southern Portugal and for the Badajoz province in Spain.
Some cooler weather and "periods and showery rain" in Northern Ireland, Scotland and western regions of England has been forecast in the coming days. EDF said the decision was made to avoid overheating the rivers.
The power plants use water from the rivers to cool down their reactors, before sending the water back into the rivers.
The World Meteorological Organization says continental Europe's record is 48 C (118.4 F) in Greece in 1977.
In Germany, state rail operator Deutsche Bahn said it was offering free water to passengers in case of delays and would keep air conditioning running on its trains even when they are empty.
In Spain and Portugal, the fire danger will climb to unsafe levels as temperatures soar, humidity levels plunge, and downslope winds increase.