Heavy rain, thunderstorms set to lash Bay of Plenty

Fresh weather warnings and watches have been issued for the Bay of Plenty and Northland in addition to those already in force for the top of the South Island.

MetService said a front was expected to move eastwards across New Zealand today and early on Thursday morning.

It would be followed by a low that moved onto the North Island.

An orange heavy rain warning was issued for the Bay of Plenty east of Whakatāne from 12pm today through till early on Thursday morning.

Rainfall totals were expected to reach up to 110mm, particularly around the ranges.

"Thunderstorms possible before dawn on Thursday," the forecaster said.

A previously issued orange heavy rain warning remained in place for the ranges northwest of Motueka, running through until 8pm today.

Up to 100mm of rain were possible, with MetService saying streams and rivers may rise rapidly.

"Surface flooding, slips, and difficult driving conditions are possible."

A heavy rain watch was also in force for the western Bay of Plenty until 1am tomorrow, alongside a previously issued watch for the Richmond and Bryant ranges in the top of the South Island.

A strong wind watch has also been issued for Northland north of Whangārei on Thursday from 3pm to 10pm, where north-west winds may reach near severe gale levels in exposed locations.

State Highway 6 is expected to reopen through the Lower Buller Gorge between Inangahua Junction and Westport at around 3pm today.

Multiple slips closed the stretch of highway on Monday, with motorists urged to use alternative routes via Reefton, Greymouth and the Great Coast Road.

However, NZTA said the reopening is weather dependent, with more forecast rain potentially impacting the progress of crews clearing the road.

"Significant work remains to redirect water back into waterways and the ongoing impacts of this are being monitored."