Bangkok braced for severe flooding ahead of a weekend high tide, with TV reports showing Thais fleeing the capital in bumper-to-bumper traffic, and international airport lounges full.
Officials could not give an exact figure on how many were leaving Bangkok as much of the traffic department's monitoring equipment was under water, Reuters reports.
Buildings across Bangkok have been sand-bagged for protection, and some vulnerable streets were nearly deserted.
The low-lying Thai capital straddles the Chao Phraya River, expected to burst its banks over the weekend during the unusually high tide that begins Friday.
Thailand's worst flooding in half a century, caused by a series of storms and unusually heavy monsoon rain, has killed 373 people dead, left more than nine million affected and or more than a third of the nation's provinces partially flooded, according to news reports.
"Picture the equivalent of 480,000 Olympic-sized pools of water trying to make their way through Bangkok at the moment," Craig Steffensen, Asian Development Bank's country director for Thailand, told CNN Friday. "Combined with the floodwaters trying to get out and the tides coming in...we could see a perfect storm in Bangkok."
Prime Minister Yingluck Shinawatra reportedly said officials were considering a proposal to dig channels in roads to drain water into the Gulf of Thailand.
The economic impact of the flooding is already being felt, with thousands of inundated factories forced to shut down, putting more than half a million people temporarily out of work, AFP reports.
From GlobalPost's Patrick Winn: Bangkok is sinking (interactive map)
"Thailand's central bank on Friday slashed its economic growth forecast for the kingdom this year," with the economy projected to grow only 2.6 percent in 2011, down from the expected 4.1 percent, AFP reports.
Tourism has also been hard-hit: Roads around the Grand Palace, normally bustling with tourists, are partially flooded. On Friday morning, AFP reports, a motorcycle taxi driver caught a snake six and a half feet long in front of the palace. Crocodiles have reportedly also escaped from flooded farms.
More from GlobalPost: Bangkok is sinking (Interactive map)