Severe winds have also been forecast.
Ms Russell said the rain band was slowly drifting south. "The severe weather warning for the rain for the Western Bay of Plenty and Rotorua, we are expecting that to continue until midnight Wednesday."
She said the warning indicated the increased likelihood of slips and flooding and people should be on alert.
The wild weather had forced contractors to postpone scheduled night works on the Poike Rd roundabout on State Highway 29 until further notice.
A New Zealand Transport Agency spokes-woman said pavement repair work planned to take place at the roundabout and its approaches was due to start on Sunday night through to Monday, June 16.
It would now be postponed until the weather cleared, she said.
The spokeswoman warned the weather was likely to make driving conditions difficult and urged people to adjust to the conditions and keep up to date with road closures and travel advice at www.highwayinfo.govt.nz.
Motorcyclists and those driving high-sided vehicles should exercise extreme caution, and all drivers are advised to reduce their speeds and increase following distances during periods of heavy rain, she said.
