The rainfall may lead to more slips on the West Coast and Marlborough as the soil is still sodden from flooding on the weekend.
"People are advised to keep up to date with the latest forecasts in case parts of the Watch are upgraded or further areas are added," a MetService spokesperson said.
Hundreds of people were forced from their homes when heavy rain caused flooding, closed major roads, submerged fields and prompted Buller and Marlborough to declare local states of emergency.
There were around 100 people still staying in three evacuation centres on Tuesday, including a school where people were camped out in classrooms.