The Department of Disaster Prevention and Mitigation has warned of possible flash floods and run-off nationwide on Wednesday and Thursday due to increased rain.

The warning, which includes Bangkok, was issued Tuesday night after Thailand officially entered the wet season last Friday.

Meteorologists forecast heavy and very heavy rain in the North, Northeast, Central Plains and the western coast of the South from Tuesday to Thursday.

They also warned of strong waves in the southern provinces of Ranong, Phangnga, Phuket, Krabi and Trang during the same period.

Heavy and very heavy rains were possible as a strong southwest monsoon has covered the Andaman Sea, Thailand and the Gulf of Thailand and a low-pressure area has developed along the coast of upper Vietnam.