The month of September has been the hottest in mainland France since records began in 1900, the country's weather office has announced, as the late heatwave looks set to continue.
Meteo-France on Friday said the average temperature of around 21.5C was "way above normal" for September, smashing previous records set in 1949 and 1961.
The average was 3.5 to 3.6 degrees more than seasonal norms, climatologist Christine Berne told journalists.
Only two other months have ended with a similar heat anomaly: February 1990 (+4C), and August 2003 (+3.7C), Meteo-France said.
Climate experts say this is part of an uninterrupted 20-month period of hotter-than-usual seasonal averages.
"Climate change is favouring an extension of hot periods towards spring and the month of September, even October," as predicted by modelling by experts of the UN's IPCC climate body, Berne said.
Weather experts warn France's unusually late heatwave is reason for alarmAutumn heatwave
The month of October is also threatening to break records.
Forecasters say France can expect temperatures well above seasonal norms for the first weekend of October, with average temperatures of between 25C and 30C in southern France.
On Sunday - the first day of October - forecasters expect more temperature records to be broken as a "heat dome" moves across the country.
France's exceptionally high temperatures are part of pattern seen elsewhere around the world.
June, July and August were marked by heatwaves, droughts, flooding and fires in Asia, Europe and north America.
UN warns of 'climate breakdown' after searing summer heat
Global temperatures stand at around 1.2C above pre-industrial levels and IPCC experts warn the 1.5C target agreed in Paris in 2015 may be breached.
"Until we reach carbon neutrality, heat records are going to be systematically broken week after week, month after month, year after year," Francois Gemenne, lead author of the latest IPCC report, told the AFP news agency.
"It's possible that reality will go a little beyond the models."