Drainage and Sewerage Department director Sanya Cheenimitr said continuing rain since last night in the capital was influenced by the downgraded low pressure cell from the storm Gaemi.
The rain has continued all day Monday with an average rainfall of 30 millimetres and water drainage in the canal network is functioning normally.
Government workers from the city and various agencies are on duty at at-risk areas until the situation returns to normal.
The flood prevention centre of the Bangkok Metropolitan Administration reported the highest rainfall at 29 millimetres in Yannawa district so far today.
The meteorological department forecast rain will continue for next two days before gradually subsiding.
Meanwhile, passenger commuter boat service in Saen Saeb canal is operating from Wat Sriboonrueng temple pier to Pratunam pier as water level is low from Pratunam to Phan Fah bridge after municipal workers drained water from the canals in preparation for the rain.