Istanbul has had its heaviest rainfall in 84 years, governor Davut Gul said. People died in the floods.
The danger of torrential rain and strong wind in Istanbul and the Marmara region has not passed, meteorologist Dr Guven Yozdemir of Istanbul Aydin University warned.
Sariyer, Kagithane, Eyupsultan and Basaksehir were hit hardest. Streams burst their banks, streets filled with water and many cars were left under water. Homes and businesses are flooded. Transport is disrupted, people were stuck at their workplaces, and cars are struggling to move.
The rain began overnight and grew heavier the next day, at different times in different districts.
"According to AKOM data, between 130 and 273.1 kilograms of rain per square metre fell in some of our districts," said Nuri Aslan, acting mayor of Istanbul Metropolitan Municipality. Beykoz had the most, with 273.1 kg per sq m, followed by Sariyer with 208.1 and Eyupsultan with 202.8. In the other districts, rainfall was between 35 and 120 kg per sq m. During the night alone, about 45 kg per sq m fell in parts of the Anatolian side.
Interior minister Mustafa Ciftci said rainfall reached 272 kg in places. Authorities received 9,588 calls for help, including 6,728 in Istanbul, and most have already been dealt with. A total of 46,097 people are working on the ground, and the crisis agency AFAD is coordinating the response.
"The 2,727 of our citizens who were stranded were evacuated safe and well," Ciftci said. The evacuation in Ayazaga is now over.
In a statement at AFAD's provincial directorate, Gul offered condolences to the families of the dead and sent good wishes to the city's residents.
Dr Yozdemir said the floods came from cold air from the Balkans meeting a rain system over the central Mediterranean. The cold widens the temperature gap and makes the air less stable, while moisture from the Marmara and nearby seas feeds the rain. Rain cells pass one after another over the same places.
Not only the amount of rain is dangerous, but the short time it falls in, the meteorologist said. This overloads the infrastructure and leads to flash floods and transport problems.
He called for extra care near streams, in low-lying areas, in underpasses and at places in Istanbul that have flooded before. Precautions are also needed in Kocaeli, Sakarya and Yalova. In strong wind, it is best to stay away from trees, billboards and roofs. Yozdemir advises people to follow warnings from the General Directorate of Meteorology and AKOM, because the intensity differs from district to district.
Torrential rain and strong wind continue in Istanbul today, and it is raining very heavily in places in Kocaeli, Sakarya and Yalova. Tomorrow the rain continues in Istanbul and eastern Marmara. On Saturday it will rain again across Marmara, with locally heavy downpours in the east, and on Sunday rain is possible in the east. On Monday Istanbul is expected to see its first noticeable improvement, with broken cloud.
The northerly wind in Marmara will blow at 50 to 80 km/h, and temperatures in Istanbul will be around 15 to 18 degrees.
Monday's improvement does not mean the end of the rainy spell, Yozdemir warned. There will be some sunny days until the end of October, but he said it is too early to talk about lasting warm weather. Lighter rain will not bring warmth straight away, because cool northerly air pulls down daytime temperatures, and mornings and evenings will be colder.
A few days of downpours do not prove that winter will be very cold, wet or snowy, the meteorologist said. He added that it is too early to say whether it will be harsh. That will depend on the polar vortex, the position of the jet streams, the North Atlantic Oscillation and pressure systems around the Mediterranean. Until the end of autumn, people should be ready for heavy rain and short cold snaps.
Seasonal forecasts only give a trend, Yozdemir said. Specific cold waves and extreme rainfall can be predicted only with short-range forecasts.