Millions of Istanbulites struggled and waded to work on Tuesday morning after early-morning thunderstorms boomed over the city, dumping torrents of rain and swamping transport networks.
Flash flooding saw main roads turned into rivers, with many soaked commuters forced to abandon submerged vehicles.
Many underpasses, intersections and some metro and bus stops were put out of action, leaving thousands of pedestrians stranded, according to Anadolu Agency reporters around the city.
Drenched commuters could be seen wringing out wet clothes or going barefoot after abandoning sodden footwear.
A metro line running from Ataturk International Airport on the city’s European side was flooded, and similar scenes were recorded at the Avrasya (Eurasia) road tunnel, opened in December 2016.
The city's tram service between the Bagcilar suburb to Kabatas on the banks of the Bosphorus was also suspended.
Many buildings and offices were flooded as swirling waters tore down trees and utility poles. A number of minor traffic accidents have been recorded so far, Anadolu Agency correspondents report.
Istanbul governorship warned people to leave their vehicles at home where possible, to prevent further road problems.
Many of Istanbul’s 15-million-strong population rely on ferries for daily journeys but the extreme weather has also hit sea travel.
Istanbul Sea Buses and Fast Ferries Operators (IDO) cancelled some ferry services.
According to forecasters there may be no let-up in the rain, with Istanbul expected to see more downfalls in the afternoon, continuing until evening, together with strong wind.