Concern has been raised especially for people living close to rivers in Tak and Ayutthaya provinces where waters are rising quickly.

Forecaster Pensiri Trisat, of the Northern Meteorological Centre, said yesterday tropical cyclone 01B in the Bay of Bengal crossed into Burma at 4am and weakened at 10am to a depression moving north-westward at about 10 kmh.

The depression would bring heavy rain all over Thailand, especially in Mae Hong Son, Chiang Rai, Chiang Mai, Lamphun, Lampang, Phayao, Nan, Phrae, Uttaradit, Tak, Sukhothai, Kamphaeng Phet, Nakhon Sawan, Uthai Thani, Kanchanaburi, Chantaburi, Trat, Ranong, Phang Nga, Phuket and Krabi, she said.

Many northern areas had had torrential downpours in the 24 hours to yesterday afternoon.

Doi Inthanon in Chiang Mai's Chom Thong district had 42 millimetres of rain, Phayao's Muang district had 43 and Uttaradit's Muang district 66. Chiang Mai town recorded 89.3 millimetres.

People in risky areas should beware of flash floods over the next two days but the situation should improve by the weekend, Pensiri said. She urged boat owners in the Gulf of Thailand and the Andaman to proceed cautiously. Small craft should not venture out to sea.

Chiang Mai's Fine Arts Office ordered officials to keep a close watch on ancient ruins and temple sites in light of the irreparable damage done to Wat Phan-on's pagoda some time ago. In Tak's Sam Ngo district, two weeks of downpours have caused the Wang River to overflow and erode its banks, including an 80m-long and 10-metre-wide section of Wang Chan-Yokkrabat Road.

Residents living in riverside houses were fearful rising torrents would cause their homes to subside. As a precaution, locals have moved belongings to safer ground.

In Phob Phra district, a flash flood hit a Hmong village in Tambon Khirirat late on Monday night damaging 50 homes and felling power poles, leading to a blackout. Officials were dispatched to assist the affected residents.

Meanwhile, the Chao Phya River in Ayutthaya had risen by 50 centimetres and many branches had over-flown, inundating low-laying communities in Muang Phra Nakhon Si Ayutthaya and Bang Ban districts. Residents were forced to wade through water to save their possessions. Many feared a repeat of last year's devastating floods.

Supoj Towijakchaikul, head of the Water Resource Department's Mekkala Centre, said levels of the main rivers were approaching crisis point due to the accumulated rainwater since last week causing many to overflow.

Riverside villagers were shifted out of areas such as the Mae Kha water station in Chiang Mai's San Patong district. Flood warnings were issued for risky areas that were flooded last year along the Chao Phya, Oing, Wang, Yom, Nan, Pasak, Tha Chin, Bang Prakong, Chi and Mul rivers.