The plane, which had been dropping water, came down on a hillside close to the town of Karystos on the Greek island of Evia, east of Athens. The captain and co-pilot, aged 34 and 27, both died, the air force said.
Greece has been particularly hard hit by fires, with authorities evacuating more than 20,000 people in recent days from homes and resorts in the south of the holiday island of Rhodes.
Close to 3,000 holidaymakers had returned home by plane as of Tuesday, according to figures from the Transport Ministry, and tour operators have cancelled upcoming trips.
The fires will deal a blow to a tourist industry that is a mainstay of the Greek economy. It accounts for 18 percent of gross domestic product and one in five jobs, with an even greater contribution on islands such as Rhodes.
Italy also suffered a twin pounding from the elements when severe storms battered the north, killing a woman and a 16-year-old
Girl Scout, while southern regions sweltered. In the south, a 98-year-old man who was bedridden died when fire swept through
his home.
Extreme weather throughout July has caused havoc across the planet, with record temperatures in China, the United States and southern Europe sparking forest fires, water shortages and a rise in heat-related hospital admissions. The heat, with temperatures topping 40 degrees Celsius (104 degrees Fahrenheit), is well in excess of what usually attracts tourists to southern European beaches.
The high temperatures and parched ground sparked wildfires in countries on both sides of the Mediterranean.
In North Africa, Algeria was fighting to contain devastating forest fires along its Mediterranean coast in a blaze that has already killed at least 34 people. Fanned by strong winds, fires also forced the closure of two border crossings with neighbouring Tunisia.
Wildfires also broke out in the countryside around Syria’s Mediterranean port city of Latakia, with authorities using army helicopters to try to put them out.
Scientists have described extreme heat as a “silent killer” taking a heavy toll on the poor, the elderly and those with pre-existing medical conditions.
Research published this month said as many as 61,000 people might have died in Europe’s sweltering heatwaves last summer, suggesting preparedness efforts are falling fatally short.