- On Sunday, people in towns and villages, including the historic site of Marathon, were ordered to move to safer areas.
- More than 700 firefighters and 119 vehicles have been deployed to put out the flames, with many volunteers also contributing.
Thousands of residents have been evacuated from their homes as large wildfires reach the suburbs of Athens, with some flames leaping as high as 25m (80ft).
Homes and properties in nearby towns such as Varnavas, as well as northeastern parts of the Greek capital are on fire, including a school in Nea Penteli.
Dozens of aircraft are working to extinguish the flames, but with sunset just hours away they will be forced to land, making it a ground operation overnight.
Residents are complaining there are not enough fire trucks and firefighters to help, as Greek authorities request international assistance.
Help is expected from Spain, Italy, Turkey, Romania and Canada, with France also providing a Super Puma utility helicopter and the Czech Republic sending 75 firefighters and 25 vehicles.
In unprecedented scenes, people in Athens are wearing masks to protect themselves from the choking smoke that has filled the air, as they try to put out flames.
A human chain of firefighters, volunteer firefighters, police officers and citizens are using everything they have to try to put fires out, with some resorting to tree branches.
Strong winds are also aiding the rapid spread of fire.
Earlier on Monday, fire brigade spokesman Vassilis Vathrakogiannis said winds were up to seven on the Beaufort scale, indicating a moderate gale force.
After more than 24 hours of fires, thousands of people have been ordered to evacuate, with some refusing to in order to save their homes.
A message from emergency services is calling on residents of the capital's northern suburb of Dionysos to evacuate toward nearby Kifissia. Thirty such localised messages have been sent.
On Sunday, people in towns and villages, including the historic site of Marathon, were ordered to move to safer areas.
More than 700 firefighters and 119 vehicles have been deployed to put out the flames, with many volunteers also contributing.
One fire is raging around Mount Penteli, famous for its marble quarries, and the adjoining Athens suburb of the same name where three hospitals have been evacuated.
The National Observatory of Athens in Penteli is also under threat, as the flames burn through some of its facilities.
Parts of the capital have been left under clouds of thick brown smoke.
Greece has just experienced its hottest June and July on record.
Climate crisis and civil protection minister Vassilis Kikilias warned that extremely dangerous weather would continue.
Greek PM Kyriakos Mitsotakis returned to Athens on Sunday, cutting his holiday short, to deal with the crisis.