Buller Civil Defence is advising people in parts of Westport to self-evacuate.
The areas include the Orowaiti Overflow area (Snodgrass), as well as Forbes and Coates Streets and the Gladstone Street area.
The notice is based on updated forecasts and flood modelling.
Local welfare arrangements are also being activated in Sedonville and Mokihinui due to the risk of river flows similar to or higher than those in February 2022.
Controller Al Lawn said the latest advice from the flood modellers, NIWA, hydrologists and information from MetService predicts a reduction in the event intensity.
The forecast ranges for river levels have been reduced, but the Orowaiti Overflow area, Forbes and Coates Streets are still considered vulnerable.
“We don’t make this recommendation lightly but we know people need time to plan and prepare. We are taking a precautionary approach and asking people to move in daylight to avoid the risk of moving in the dark, placing themselves and our emergency responders at risk.”
He said please consider your own circumstances and act now.”
More significant rainfall is set to come through Wednesday and Thursday. Voluntarily self-evacuation is underway in the low lying areas in Westport shown in the maps.