Greek authorities warned the public against unnecessary movement on Friday and said there was a high risk of wildfires during a "dangerous" heatwave that is expected to peak next week.
Temperatures have been high in much of the country in recent days and are expected to reach 44 degrees Celsius (111.2°F) next Monday and Tuesday, the National Meteorological Service said.
Neighboring Turkey has been hit by wildfires this week in which four people have been killed, Reuters reported.
"A difficult weather phenomenon is coming in the next days with extremely high temperatures and several days of heatwave," Citizens' Protection Minister Michalis Chrysochoidis told reporters. "I call on - I urge - everyone to show the highest degree of responsibility and cooperation."
Theodoros Kolydas, head of the weather service, said the heatwave was characterized as "dangerous" because it was expected to last several days -- at least until next Friday, with the peak expected on Monday and Tuesday.
Earlier this month, Athens Mayor Kostas Bakoyiannis appointed a chief heat officer, the first in Europe, to help the capital tackle extreme heat.
Firefighters have tackled more than 40 wildfires in the last 24 hours, the fire brigade said, fanned by winds high temperatures. A raging blaze north of Athens on Tuesday burned at least a dozen homes before being brought under control.
More than 1,000 people were killed in 1987 in Greece's deadliest heatwave, with scorching temperatures in the country for over a week.