Greek authorities have warned people to stay in their homes and keep “the windows closed” as 400 firefighters on the outskirts of Athens battled to control fires that have forced the evacuation of entire communities.

Huge clouds of smoke darkened the skies over the capital on Sunday afternoon as ten groups of “forest commandos”, supported by firefighting planes, helicopters and fire trucks, tried to extinguish flames fanned by squalls. Volunteers also joined the fight near the village of Varnava, about 35 kilometers north of the city.

“The emergency services are being continuously reinforced, but they are facing flames that are in many cases more than 25 meters high,” said fire department spokesman Vassileios Vathrakogiannis.

While one fire in western Attica was brought under control, a second fire northeast of Athens was still not contained. By nightfall, the inferno was reportedly racing eastward as the efforts of firefighting aircraft were thwarted by strong winds. At least 10 communities around Varnava have been evacuated and firefighters are expected to continue working through the night.

Health officials urged people to limit their movements and stay indoors as the thick smoke had seriously affected air quality across the Attic Basin. By 4 p.m., the sky above the Greek parliament in central Syntagma Square had turned yellowish-brown as ash clouds drifted southward, driven by winds.

At least eight people were hospitalized with breathing problems.

Environmentalists warn that after the warmest winter on record, unprecedented temperatures – June and July were the hottest months on record – have turned Greece into a powder keg.

For the first time this summer, the country experienced a week-long heatwave before mid-June, a sign of the ever-accelerating progress of climate change.

At least 10 tourists, including respected British nutritionist and television presenter Dr Michael Mosley, are believed to have died earlier this summer from heat exhaustion while walking in scorching heat. Mosley is believed to have died less than two hours after setting off on a hike from a beach on the remote island of Symi in temperatures of over 40 degrees Celsius.

Greece has been hit by hundreds of forest fires in recent months.

Sunday’s strong winds show no signs of abating and meteorologists predict that the coming days are likely to be critical.

At least half of the country is expected to be on red alert, indicating the increased risk of forest fires due to the weather conditions.

Speaking to state broadcaster ERT, Athens Observatory research director Kostas Lagouvardos said: “What makes the situation so dangerous is the persistent drought and the very high temperatures that have persisted for so long.”