The continued heavy rain caused forest runoff from the Phetchabun mountains to flood more than 3,000 rai of paddy fields in five subdistricts of Phitsanulok's Bang Krathum district.
It was expected that the area of flood damage could widen because water is still flowing from the mountain.
Meanwhile, the Meteorological Department of Thailand has warned that the northeastern provinces of Thailand to brace for heavy rain expected to come from tropical storm "Bebinca" that is now in Vietnam.
The weather agency said in a statement that the storm is over northern Vietnam and has been downgraded to tropical depression status. It was last reported at 100 km northeast of Hanoi with maximum sustained wind of about 55 km/hour and was moving north slowly and was expected to weaken to become a low pressure cell in the next phase.
The storm has caused heavy rain over Thailand's Udon Thani, Nong Khai, Bueng Kan, Sakon Nakhon, Nakhon Phanom and Mukdahan provinces for several days.
At the same time, the strong southwest monsoon remains over the upper Andaman Sea and the Gulf of Thailand. Strong wind and 2-3 metre high waves are expected in the upper Andaman Sea. The department warned ships to proceed with caution and for small boats in the upper Andaman Sea to keep ashore.