The worst is yet to come for Northland as Tropical Cyclone Tam moves toward the north of New Zealand this evening.

MetService meteorologist Mmathapelo Makgabutlane said the weather system was expected to be reclassified as an ex-tropical cyclone as it reached cooler waters, but would still bring wild weather.

The region remains under an orange heavy rain warning until 9pm on Thursday and a strong wind warning from 3pm today until 8pm on Thursday.

Civil Defence met with local emergency services, councils, contractors, lines companies and partner agencies earlier this morning to prepare for response where necessary.

Diversions are in place at Mata near Salmon Rd south of Whangārei on State Highway 1 due to a tree blocking both lanes.

Waka Kotahi NZ Transport Agency have advised motorists to delay their journey or allow for extra time.

Northpower is investigating six different power cuts in the Whangārei and Kaipara districts.

About 50 homes and businesses in the Maungakaramea area have been without power since 8.40am due to trees on the power lines. This is expected to be fixed by 1pm.

In the Waipu area, 50 customers have been without power since 9am due to broken power lines, which is expected to be fixed by 12.30pm.

About 750 customers in Ruatangata West have been without power since 11.15am, with reports of a tree on the line.

In Mangawhai central, about 280 customers have been without power since 11.50am due to an unknown fault.

In Morningside, about 370 customers have been without power since 11.40am, with reports of a tree on the line.

In Whakapirau, 240 customers have been without power since 11.10am due to an unknown fault.

Meanwhile Top Energy were investigating four outages at Awanui, Mangōnui, Kawakawa and Ōmāpere which has left over 650 without power in total.

Winds have already reached 100km/h in exposed places across the region, however, in the past 12 hours, around 20mm of rain has fallen.

Makgabutlane said while there may be periods of calm today, the weather would ramp up again this afternoon.

The gusts proved strong earlier today when the southbound lane on State Highway 1 near Uretiti was blocked after winds toppled a tree.

A Fire and Emergency spokesperson said they were called to the scene just after 11am and were directing traffic with help from police while crews tackled the tree with a chainsaw.

There was also trouble in Northland waters over the last 24 hours, according to Northland Harbourmaster Jim Lyle.

A 12m concrete yacht sank at Totara North however, it was not considered a navigational hazard, and there was nothing that could be done until the storm had passed, he said.

Meanwhile, another report had come through of a small yacht running aground on mud at the side of the Hatea River on Tuesday evening.

Northland Regional Council data shows the heaviest rainfall thus far was in the hills north of Whangārei, with Glenbervie Forest recording 21mm between 6am and 7am.

The largest concentration of rain was in eastern areas of the region around the Bay of Islands and Whangārei.

The worst of the rain is expected to lash western areas this evening.

Makgabutlane said people should watch out for wind speeds ramping up late this afternoon and into the evening.

Whangārei mayor Vince Cocurullo urged residents to remain vigilant.

Crews at the top of the Brynderwyn Hills were monitoring slips or damage caused in the storm so they could be rectified immediately, he said.

More crews were stationed around the community, ready to help.

Swell was building at Ocean Beach in Whangārei Heads this morning as Cyclone Tam approaches. Photo / Karina Cooper

He was liaising with emergency management staff this morning for updates and encouraged people to report damage to the council immediately.

Northland Waste have asked that only blue bins - used for glass recycling - and well-secured rubbish bags are put out for collection.

There is no collection on Good Friday and rubbish that would usually fall on that day will be picked up on Saturday instead.

Meanwhile Far North District Council have road crews are currently investigating unconfirmed reports of slips and trees blocking roads.

The Pou Herenga Tai – Twin Coast Cycle Trail has shut for the day due to weather.

There was some disruption to traffic earlier this morning as Fire and Emergency crews attended a large tree branch blocking a road in Kensington, Whangārei.

Crews arrived at 8am and had cleared the road by 8.20am. No one was injured.

Brodie Stone covers crime and emergency for the Northern Advocate. She has spent most of her life in Whangārei and is passionate about delving into issues that matter to Northlanders and beyond.