Europe is the planet's fastest-warming continent and in some places is ill-equipped to deal with hot weather. Repeated heatwaves have fuelled a historically hot summer of drought and wildfires, and contributed to the deaths of thousands of people so far.
Scientists have shown that recurring heatwaves are a clear marker of global warming, primarily caused by burning coal, oil and gas -- and warn they are set to become more frequent, longer and more intense.
Temperatures are also forecast to surpass 30C for more than half of Europe's population on Wednesday, excluding Turkey, amounting to around 300 million people, according to an analysis based on German weather service forecasts and 2025 population projections from the Joint Research Centre.
The most intense heat is expected in Western and Southern Europe. Temperatures are set to climb above 35C in regions of France home to 30 million people, though mountainous areas and the northeast of the country are expected to be spared.
Similar heat levels are forecast for 29 million people in Italy and for 21 million in Spain.
The heatwave extends toward the Balkans, notably Greece and the Adriatic coast -- including Albania and Croatia.
Further north, temperatures in the United Kingdom are expected to rise above 30C for 43 million people.
The usually-temperate country is on track to record its hottest summer ever, the official Met Office agency said Tuesday.
AFP uses a method similar to that of the Austrian NGO Klimadashboard to calculate the figures, cross-referencing population density with the weather forecast model from the Deutscher Wetterdienst (DWD) —- Germany's national meteorological service -- published at 0300 GMT.
Residents are counted if the model forecasts temperatures above 30C or 35C at their location at any point during the day.
As the model has a resolution of approximately 6.5 km it does not fully capture urban heat-island effects, when cities are significantly warmer than surrounding rural areas, David Jablonski of NGO Klimadashboard told reporters.
Consequently, the analysis "likely underestimates the number of people affected in densely populated urban areas", the organisation notes on its "European Heat Tracker" website.
