Metservice has issued a severe weather warning and heavy rain watch for the Gisborne district and is also warning of heavy five-metre swells.
The severe weather warning is for north of the city, from Sunday morning through to Monday morning.
"From 10:00am Sunday to 10:00am Monday expect 100 to 140mm of rain to accumulate," the Gisborne District Council said in a statement.
Peak rates of 10 to 20mm/h are forecast for Sunday afternoon and evening.
Further rain is expected after the warning period but is likely to be much less, the council said.
In an update Sunday morning, the council said Gisborne and south of the city are expected to experience periods of heavy rain between 3pm Sunday and 9am Monday morning. Rainfall amounts may approach warning criteria during this time.
The council also provided further information regarding the heavy swell warning.
"Easterly swells are expected to reach 3.5 metres around midday Sunday, with a period of 10 seconds or less. Strong southeast winds reach gale north of Tolaga Bay Sunday morning, and the underlying swell will be masked with large wind waves of up to 4 metres by midday. Combined waves could reach 5 metres by Sunday night."