Don Muang airport, used mainly for domestic flights, is in northern Bangkok - the area of the capital worst hit by the flooding.
The international airport, in another part of the city, is still operating.
Thailand has been hit by heavy monsoon rain since July, leading to flooding which has hit swathes of the country and left more than 360 people dead.
Officials have been trying to drain it to the east and west of Bangkok, but they have been forced to open sluice gates into the city because of the sheer volume of water building up outside Bangkok's flood barriers.
On October 25, the Thai cabinet announced a US$10.5 billion fund to help rebuild the country - mainly aimed at small and medium businesses, small vendors and individuals.
Thai authorities have declared a holiday in several provinces, including Bangkok, to help people cope with the flooding.
Schools and offices will close from Thursday through to the end of Monday, creating a five-day break.
