Qatar was hit by more than a year's worth of rain in a matter of hours Wednesday, almost bringing the country to a standstill and prompting the premier to order an inquiry.
Bad weather across the region also affected neighbouring Saudi Arabia where one person was killed during flooding.
The deluge in Doha blocked several roads, making some impassable for commuters and causing huge congestion.
Schools and malls closed, hotels were affected and the rain forced the US embassy in Qatar to shut down.
Worst hit seemed to be the area around Doha's Hamad International Airport, where almost 80 millimetres of rain fell, according to the Qatar Meteorology Department.
Social media users reported leaks at the facility, which opened just last year after being constructed at an estimated cost of $17 billion (16 billion euros).
However, Hamad International said flights operated normally throughout the day.
The World Bank calculates that Qatar receives, on average, 74 millimetres of rain each year.
In response to the scale of the problems, Qatar's prime minister ordered an investigation, said the official Qatar News Agency.
Sheikh Abdullah bin Nasser bin Khalifa al-Thani said those responsible for "flawed projects" could face possible prosecution.
"It was decided to refer all stakeholders and companies implementing the flawed projects that were revealed by the rainy weather currently experienced by the country, to investigate and then to public prosecution, the prime minister instructed," reported QNA.
As many as five unnamed companies could face prosecution, said the report, citing the government communications' office.
The scale of the disruption was especially worrying as Qatar has undertaken a more than $200 billion infrastructure programme to ensure it is ready for the football World Cup finals, which it will host in 2022.
Qatar is well-known for its fierce summer temperatures, which forced World Cup organisers to move the tournament to November and December for the first time.
Matches will be taking place at this exact point in seven years' time.
The rains also affected neighbouring Saudi Arabia where one person was killed during.
Schools were closed for a second day as rain continued to fall on Riyadh, flooding some streets and forcing drivers to abandon their cars.
About 10 cars were submerged under about two metres (more than six feet) of water in a highway underpass in the Labban district on the capital's western outskirts, an AFP photographer reported.
Workers were trying to drain the floodwaters into tanker trucks as a light rain fell from gloomy skies.
The Civil Defence agency reported that 72 vehicles had been rescued in the Riyadh region with their occupants unharmed.
One person died in Rimah, northeast of the city, the agency said.
Other parts of the kingdom have also been soaked this week.
At least eight people died in flooding last week in the Medina and Jeddah areas of western Saudi Arabia.