The Bay of Plenty regional council is advising farmers to move stock to high ground as heavy rain is forecast for the area.
MetService says 200 millimetres of rain could fall in the ranges overnight on Monday and 100mm in low-lying areas in Bay of Plenty, Northland, Auckland, Coromandel, Gisborne and Hawke's Bay.
The council's flood manager says while it is unlikely rivers will burst their banks, the intensity of the rainfall could cause flooding.
Colin Meadowcroft says there is a chance urban areas throughout the Bay of Plenty could experience flooding and roads across the region may be affected by slips.
Roads on the Coromandel peninsula could also be affected.
The Civil Defence manager for Coromandel, Ron White, says the rain could combine with a king tide on Tuesday morning and flood roads on the peninsula's east coast.
The rain could bring down slips and contractors are on stand-by to clear any roads, he says.