Flood warning as heavy rain batters Northland, Nelson and Golden Bay

Holiday travel across parts of the country is being disrupted by heavy rain, which is bringing road closures and difficult driving conditions over the King’s Birthday weekend.

People in Northland, Nelson, and Golden Bay are being urged to prepare for possible flooding as a powerful weather system moves across the country.

MetService says a trough embedded in a humid northerly airflow is bringing widespread heavy rain with some areas already recording significant rainfall and more expected over the next 24 hours.

Northland, Golden Bay, and Nelson are expected to be among the hardest-hit regions with forecasters closely monitoring conditions overnight.

While an orange heavy rain warning for Northland started at midday on Monday, MetService meteorologist Mmathapelo Marshall told RNZ that parts of the Far North were already being drenched.

"Kaitaia had close to 30 millimetres of rainfall in an hour, from 5am, which is very persistent rain," Marshall said.

Rivers are expected to rise in Tasman. Photo/RNZ/Louis Dunham

Further south, Mount Cook recorded 147 millimetres of rain in the past 24 hours while inland, parts of Nelson received about 200mm on Sunday.

Orange heavy rain warnings are in place for Westland south of Hokitika, parts of Tasman District, the Ranges of Buller, and the Richmond and Bryant Ranges. Heavy rain watches have also been issued for other parts of the South Island.

Marshall said the West Coast would also receive significant rainfall but communities there were more accustomed to dealing with high rain totals.

Emergency teams are on alert in Marlborough as rising river levels and persistent rain raise the risk of flooding along State Highway 6. Photo/RNZ/Louis Dunham

Emergency management teams are already preparing for the impact.

In Marlborough, an orange heavy rain watch remains in force until 4am on Tuesday. The district council warned on Sunday that rising water levels in the Pelorus River could lead to flooding at Dalton's Bridge on State Highway 6.

Officials have also warned that prolonged rainfall could continue into Tuesday morning if the weather system slows over the southern Richmond Ranges.

Motorists are being urged to avoid overnight travel over the next few days, particularly along SH6 through the Havelock, Pelorus and Canvastown areas, where flooding or road closures are possible.

MetService said weather experts would continue monitoring conditions closely.

"They will also have the latest model runs and they'll be able to see how the system is evolving and how it continues to evolve for the next few days."

Heavy rain warnings are also in place for Taranaki Maunga and Northland, while strong wind watches cover parts of Taranaki, Auckland and Great Barrier Island.

Forecasters say severe gales are possible in some parts of the North Island as the system tracks south.

Residents in affected areas are being encouraged to stay up to date with weather forecasts, avoid unnecessary travel where possible and be prepared for rapidly changing conditions.