"But there is a three in five chance or a moderate risk of rain exceeding 100mm in 24 hours on Saturday and the possible of gale force winds," she said.
Severe gales of up to 120km/h could hit the Waikato side of the Kaimai Range, she said.
"We know we are in for something big and people should expect it to be pretty wet and windy on Saturday."
It could also mean large coastal waves and storm surge for the northeast of the North Island, especially from Northland to the Bay of Plenty.
Worried flood-affected Matai St residents Chad Paekau, Evan Cavanagh, and Nancy Baird were already bracing themselves to respond to the potential deluge. Mr Paekau, and his girlfriend Faye Tincler, who rented their Matai St property, were flooded in April last year after heavy rain hammered the Western Bay with 218.8mm falling in 48 hours. It resulted in more than $10,000 in insurance claims for them and their landlord after knee-deep water poured through the house - the second time since 2011 they had been flooded. The floodwaters were so high vehicles could not get through and six parked cars in the street were flooded with four written off, Mr Paekau said.
Tauranga and Western Bay Civil Defence emergency management operations manager Alan Pearce said the engineering service group had already begun checking and clearing debris from stormwater drains to reduce the flooding impact in the region.
Mr Pearce said a team of council staff had been put on emergency standby and today members of the incident management team would meet to discuss the evolving weather situation and decide what other steps needed to be taken.