The lethal "heat dome" responsible for more than 1,300 deaths across Western Europe is pushing east into the Balkans, threatening temperatures up to 40°C and dragging Greece into a volatile cycle of extreme heat followed by violent storms.
The World Health Organization has linked the unprecedented system to the death toll racked up during its multi-week grip on Western nations.
Though conditions have eased in France and Britain, the World Meteorological Organization warned Monday that southeastern Europe is now the system's epicentre.
Serbia is braced for 40°C on Tuesday, while Croatia is already fighting intensifying wildfires, including a major blaze on the island of Hvar.
Greece is entering a critical 48-hour window, with temperatures forecast to reach 39°C, particularly in the northwest.
Greek pyro-meteorologist Theodoros Giannaros said Mediterranean populations are better acclimatised to extreme heat than their Western European counterparts, but warned the recurring nature of the phenomenon points to an urgent need for emissions cuts and far more aggressive climate adaptation policy.
The heat is set to give way to its own backlash. National meteorologist Dimitris Ziakopoulos said a low-pressure system tracking north from Crete will destabilise the upper atmosphere from Tuesday, triggering sudden, torrential downpours and severe storms.
The mainland's mountainous regions are expected to bear the brunt by Thursday and Friday, as Greece swings from one extreme to another within the space of a week.