Meanwhile further south, Environment Waikato's flood management staff are on alert as rivers are still high from last week's rains.
The Waikato, Taranaki and parts of the central North Island are in for heavy lashings of rain today.
Police said there are reports of surface flooding on State Highway One on the Waikato Expressway and described it as "treacherous".
They are encouraging drivers between Meremere and Te Kauwhata to drive with caution.
MetService has issued heavy rain warnings for the areas as a warm front moves across the middle of the North Island.
Forecaster Oliver Druce said thunderstorms could bring rainfalls of up to 120mm in the eastern ranges of the Bay of Plenty.
Taranaki, Raglan, the Kaimanawa Ranges and Taupo can all expect up to 100mm of rain with the heaviest falls coming tonight.
The eastern ranges of the Bay of Plenty are also in for a heavy dumping with 120mm of rain expected in the 16 hours from 8am.
Mr Druce said up to 25mm could fall in the space of an hour during the thunder storms.
Heavy rain has caused mining to be suspended at the country's largest open pit gold mine at Waihi, in the Bay of Plenty.
Newmont Waihi Gold Company has closed the mine until further notice, due to instability on its eastern wall.
The stability of a tyre buttress on that wall was being investigated, company spokeswoman Linda Willoughby said.
Access roads and other facilities above the buttress had been closed as a precaution.
- NZHERALD STAFF with NZPA
