The Meteorological Department is warning 17 provinces to brace for possible flash floods.
The flood-prone areas are mostly in the North, the East, and the upper South.
They are Chiang Mai, Chiang Rai, Lamphun, Lampang, Phayao, Phrae, Nan, Uttaradit, Phitsanulok, Sukhothai, Tak, Phichit, Phetchabun, Chanthaburi, Trat, Ranong and Phangnga.
A low pressure cell has been covering the upper part of the North, while the southwest monsoon lingers over other areas, the Andaman Sea and the Gulf of Thailand, said the department in its warning issued this morning.
The combined effects of these two weather conditions could result in flooding in the 17 provinces.
With high seas of two to three metres predicted in the Andaman Sea and the upper part of the Gulf of Thailand, small boats were advised to remain ashore on May 10-12, said the department.
In Lampang, several parts of the Muang municipality have been flooded by the overflow of water from Mae Wang River. All flights to and from the provincial airport were cancelled today as it was unsafe for landing and taking off.
The flooding in this province has also trapped two trains – one from Chaing Mai to Lampang and the other from Bangkok to Chiang Mai – in an area where the rail tracks are heavily flooded.
Passengers were transferred to public buses that took a different route to their destinations.
In neighbouring Lamphun province, rescue workers were speeding up efforts to evacuate villagers in a number of flooded areas of Li district.
Several familes were waiting on the roofs of their flooded houses when the rescue boats reached their communities, said Wuthiphong Chanturat, chief of the district office.