Coromandel residents are this morning assessing the damage after being caught out by fast-rising floodwater after the heavens opened on Sunday.

Cars were left stranded on flooded roads and homes are water-logged after the North Island was drenched in rain.

Coromandel G.A.S petrol station was closed on Sunday due to floods. Photos: Thames Valley Civil Defence.

Many fences are reported down overnight as farmers waited for the morning to see if livestock in flooded paddocks have made it through the night.

Tellic Evans from White Star Honey at Colville at the northern end of the Coromandel Peninsula says 174ml of rain fell on her farm on Sunday.

A severe weather watch was upgraded to a warning at 6.30pm on Sunday, but Tellic says by then it was too late.

"It' had already hit us by then.

Flooding in Colville, in the Coromandel, on Sunday.

Paddocks and fences are damaged, neighbours closer to the foreshore have already lost stock and a number of homes were surrounded by flood water, as reported by Stuff at 10pm.

The Colville School is also affected.

The Coromandel Peninsula and parts of west Auckland bore the brunt of the heavy downpour.

The rain stopped at about 9pm.

One car had to be rescued while driving through water in Albert St, Coromandel, while the nearby town of Colville was flooded.

Fire Service shift manager Daniel Nicholson says a driver was trying to get through a "small river of water" in Coromandel at 4.50pm.

They were trapped in their car as they attempted to get to higher ground but were eventually freed.

Fire crews also responded to floods in Colville at 5.30pm.

MetService had warned of heavy rain in Northland brought upon by a trough of low pressure moving southeast from the subtropics.

In Auckland there were consistent showers during the day, with several flooded houses west of the city.

A loungeroom in a Ranui home was flooded, while a basement of a house in Titirangi was flooded, requiring portable pumps to get water out, says Daniel.

MetService says a trough of low pressure was moving slowly across Coromandel Peninsula and western Bay of Plenty, and would then move east to the Bay of Plenty and northern Gisborne overnight.

Residents were advised that it could cause rivers and streams to rise rapidly, with possible slips and surface flooding.

Additional reporting - Stuff.co.nz