The fires began on Thursday and soon threatened three villages in the state of Brandenburg, outside Berlin. The towns of Klausdorf and Tiefenbrunnen were evacuated, with locals either fleeing to the homes of friends and relatives or being housed in local shelters. Residents in the village of Frohnsdorf were allowed to return to their homes Friday afternoon.

The unusually hot summer and drought in Germany meant the fire quickly spread through dried-out pine forests. Many areas have had to enforce campfire and grilling bans.

Reports suggested that smoke from the blaze could be seen as far away as 10 kilometers (around 6 miles). Social media users in Berlin said on Friday that they woke up to the sight of smoke in the distance.

By Saturday, authorities said the fire had affected some 400 hectares of land and Berlin residents were told to keep their windows and doors closed to keep out smoke.The fire set off some undetonated World War II and Soviet munitions dumped in the ground, hampering firefighting efforts.

More than 500 people have had to flee the fires. Authorities said they had made some progress containing the fire with low winds coming to their aid, but the situation was unlikely to improve over the next few days.

"We've had forest fires before, but never of this magnitude," said Mayor Michael Knappe of Treuenbrietzen, another town in the area. The cause of the fire was initially unclear, but authorities announced that "all indications" now suggest the fire could have been caused by arson.

Summer 2018 began as a welcome break from Europe's often-unpredictable weather, and people took advantage of the constantly warm temperatures to spend more time outside. The heat was especially a boon for pubs and bars where fans congregated to watch the soccer World Cup. But as temperatures climbed to up to 39 Celsius, the heat wave's negative effects began to be felt across the continent.

The high temperatures and low rainfall led to a sharp rise in wildfires across several European countries, including Sweden, where authorites were, at one stage, battling more than 50 blazes, some in the Arctic Circle. When German firefighters tackled a forest fire in Fichtenwalde, near Berlin, their operation was suddenly made more urgent by the discovery of unexploded World War II ammunition.

Greece, meanwhile is counting the cost of its own devastating wildfire which last week left 86 people dead. The seaside village of Mati, just 30 kilometers (17 miles) from Athens, saw houses and land incinerated, while many people drowned after rushing into the sea or were burned alive while trying to escape in their cars.

Many of Europe's rivers and reservoirs experienced almost drought-like conditions after water levels dropped severely. Freight vessels that ply German sections of the River Rhine (pictured here in Düsseldorf) and Danube were ordered not to sail fully loaded. The Netherlands meanwhile closed several movable bridges after the metallic structures expanded so much that they couldn't be opened.

As millions of Europeans hit roads, rail and air for their annual summer holidays, transport infrastructure struggled to cope. Eurotunnel passengers faced delays of up to five hours after the air conditioning units failed on trains. Some holidaymakers were forced to spend the night at Hanover airport after authorities canceled flights when one of the runways started to melt.

Poland shut scores of beaches along the Baltic Sea coast after the heat wave triggered a massive toxic algae bloom. German health officials, meanwhile, warned the elderly and others with weaker immune systems to avoid swimming in the Baltic Sea as the increased water temperature poses a danger from vibrio bacteria, which can cause severe illness.

German farmers estimated the damage to crops from the heat wave could reach €1.4 billion and warned of higher supermarket prices. Other countries predicted the worst grain harvest in 25 years, as crops ripened much faster than expected and low rainfall produced a low yield. In Sweden, dairy farmers said they were being forced to slaughter some of their livestock.

Until storms broke the intense heat on Friday evening, Parisians made use of the city's recreational facilities to keep cool, including water fountains around the Eiffel Tower. Despite being 3,324 pages long, France's infamous labor code doesn't mention a specific temperature that would force companies to shut down. But staff can't be punished if they stop work over fears for their health.

Parts of Europe experienced up to six weeks of uncomfortably hot weather. Forecasters predicted that the first storms would bring heavy rainfall to many areas this weekend. Thunder, rain and hail were reported in France and the UK on Friday evening, while the darkening clouds alerted the crowd at this cricket match just outside the English city of Leeds to prepare for a similar downpour.