Temperatures on Tuesday are expected to reach 36 degrees Celsius for a second day in a row, and to inch up even higher on Wednesday, according to the Hellenic National Meteorological Service (HNMS), which forecasts cooler weather as of Friday.
In Attica, temperatures are expected to reach a daytime high of 36C, with light winds doing little to alleviate the heat.
In Thessaloniki, high levels of humidity in combination with temperatures reaching 33C are expected to make for an oppressive couple of days.
Hot weather with temperatures reaching 37C are expected on Tuesday throughout the eastern mainland and Evia, with the Ionian also experiencing highs of around 35C.
The islands of the Aegean, and the Cyclades specifically, will be more fortunate with slightly stronger winds taking the edge off the heat.
On Wednesday and through Thursday, the HNMS forecasts highs of up to 39C in parts of mainland and eastern Greece, with temperatures easing off significantly from Friday.