Travellers using Nakhon Si Thammarat airport are advised to allow at least three extra hours for travel to and from the airport because of severe traffic congestion on flooded roads.
The airport said on Monday morning it remained open with no flights cancelled.
However, flooding on the roads to the airport was severe. Passengers should allow at least three hours extra to get to and from the airport. Drivers of small vehicles were warned of the need for extreme caution.
Nakhon Si Thammarat is the province hardest hit by the flooding in provinces along the western side of the Gulf of Thailand. Floodwater ravaged the city and other districts on Monday morning.
The Meteorological Department on Monday warned of rain throughout the day and big waves at sea, continuing into Tuesday.
A small boats warning is in effect for the area.