Auckland, Northland and Coromandel are set to bear the brunt of the wet weather today with power company Vector poised to repair power outages caused by the wild weather.
Severe weather warnings are in place for the regions, where up to 150mm of rain is expected to set in, that could cause streams and rivers to rise rapidly, surfaces to flood and banks to slip.
Vector's head of field services Marko Simunac said crews were ready to respond to outages caused by the wet and windy conditions that were due to set in overnight last night and last until Tuesday.
"We are monitoring the weather and have crews ready to head out if they're needed. We know power outages are no fun, especially if it's cold and wet outside. People can be reassured we'll do everything we can to fix any power outages as quickly as possible."
Niwa warned the risks of slips and flooding in the Coromandel were growing, as holidaymakers who escaped to the getaway hotspot for the long weekend begin their commute home.
Rainfall modelling for the next 48 hours predicts totals in the region to reach 300mm.
In Coromandel, a heavy rain warning is in place until Tuesday afternoon.
People in the area can expect periods of heavy rain and driving conditions could be dangerous.
Strong winds are also possible in the region and could become severe in exposed places.
The entire Northland area is under heavy rain warning until Monday afternoon.
Parts of the region have already seen heavy rain across the weekend – with Kaikohe recording 76mm of rain in the past 24 hours, according to MetService.
The rain is set to hang around Whangārei and Kaitaia until Wednesday when the weather turns partly cloudy with a high of 20C.
But the rain clouds are expected to return to the area by Friday and stay for the weekend.
Rain will also soak Auckland on Monday with some heavy falls expected north of Albany and strong northeasterlies in exposed places.
Queen's Birthday – June 7 – Forecasts
Whangārei: Periods of rain, with some heavy falls. Strong easterlies, gale gusting 100km/h. High of 18C, low of 13C.
Auckland: Periods of rain, with some heavy falls north of Albany. Northeasterlies, strong in exposed places. A heavy rain watch is in place until 1pm. 16C/13C.
Hamilton: Cloudy, with periods of rain. Easterlies, gusty by afternoon. 16C/11C.
Tauranga: Periods of rain. Strong northeasterlies. 17C/13C.
New Plymouth: Periods of rain that ease in the evening. Northeasterlies. 17C/10C.
Rotorua: Rain. Gusty northeasterlies. 14C/10C
Napier: Cloudy. A few showers, becoming frequent in the afternoon. Fresh northeasterlies. 17C/13C.
Wellington: Cloudy with occasional early rain, then fine spells. Chance of an evening shower. Southeasterlies. 16C/10C.
Nelson: Periods of rain clearing in the afternoon but remaining cloudy. Southeasterlies. 16C / 9C
Christchurch: Periods of rain turning to drizzle in the evening. Light winds. 12C/7C
Dunedin: Cloudy at times. Light winds, then northeasterlies from afternoon. 12C/6C.