WELLINGTON - Heavy rain over much of New Zealand's North Island has caused slips and flooded roads, and forced the evacuation of a camping ground.

Roads and houses across Auckland have been flooded, and farmers in Northland, Bay of Plenty and Waikato, have been told to move stock to higher ground, police said on Sunday.

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The east coast of Northland received 200 mm of rainfall overnight Saturday, and part of Rawhiti Road near Taupiri Bay collapsed.

Police said people should restrict travel on the Coromandel Peninsula around Whitianga due to floods, slips and fallen trees, after nearly 100 mm of rainfall was recorded in a 24 hour period since Saturday.

In Auckland, the Transport Agency said city-bound lanes of the Northern Motorway have been closed by tidal debris between Esmonde and Onewa Roads.

The North Western motorway is closed over the Waitemata Harbour causeway.

The police in Auckland said waves crashing over the sea wall have closed Tamaki Drive at Ngapipi Road, and many other roads across the city are affected by flooding.

The Fire Service said it's been kept busy because of flooded houses across the city.

Strong winds have brought down trees in Waikato partially blocking State Highway 23 and Ohautira Road near Raglan.

About 300 holidaymakers were being evacuated from the Spa Park camping ground in Taupo in preparation for widespread flooding. The low-lying camping ground is next to the Waikato River.

Bay of Plenty Regional Council said several rivers in the region had reached early warning levels after 100mm of rain fell in eastern Bay of Plenty in 24 hours.

The Otara, Waimana, Waioeka and Mangorewa rivers reached their first warning levels on Sunday morning and council staff were preparing pumping stations.

Bad weather has also forced the cancellation of the final day of the popular Wings Over Wairarapa air show at North Island town of Masterton.

MetService forecaster Raveen Das said the rain would continue through much of Sunday.

Gale force south-easterlies in exposed areas were expected to turn into north-easterlies.

As much as 400 mm of rain could fall in some areas until Monday morning.