A severe weather watch has been issued for the Bay of Plenty for tomorrow and Thursday with the possibility 200mm of rain could fall.
According to the Metservice, a strong northeasterly flow is expected to bring a very warm and moist air mass onto the country on Wednesday and Thursday.
This was likely to bring warning amounts of rain and severe gales to many areas.
Rainfall accumulations could reach warnin amounts in the Bay of Plenty, Northland, Auckland, Taranaki, Coromandel Peninsula, Rotorua, Taupo and the far north of Gisborne.
A band of heavy rain was expected to move onto Auckland and Taranaki on Wednesday evening and then spread east during Thursday.
The heaviest rain was expected to affect Coromandel Peninsula and the Bay of Plenty where total rainfall accumulations could reach about 200mm. There would be potential for flooding, slips and hazardous driving conditions.
Civil defense issued an alert about the weather watch, saying they expected to upgrade it to severe weather warning tomorrow morning.
"This has the potential to be a significant weather event for the Bay of Plenty," it said.