Key Points:

Up to 80mm of rain was expected to be dumped over Northland overnight with authorities on standby last night over the prospect of flooding.

The MetService issued a severe weather watch over Northland and northern Auckland yesterday, as a low and associated front were forecast to slowly cross the northern parts of the country.

The heaviest falls were expected over the eastern hills north of Orewa from yesterday evening, lasting through to this afternoon.

Weather ambassador Bob McDavitt said 60-80 mm of rain was expected over Northland over a nine-to-12-hour period. Flooding was likely.

"The whole of Northland is under the target of that incoming juicy rain belt."

Auckland gets off lightly, receiving only 10-20mm of rain over the same period. "It's pretty thin over the Auckland area."

It was part of the same front which plagued the South Island and lower North Island yesterday, said Mr McDavitt.

Eastern parts of the North Island such as Gisborne get the rain today.

There was a chance the situation in Northland could be upgraded into a severe weather warning, he said.

Whangarei District Council spokeswoman Ann Midson said there were contingency plans in place should the weather get worse.

"It's just light consistent rain [now], we're expecting it to intensify according to what we've been told by the MetService.

"At this stage, we're all just working away in our normal fashion, expecting it to get rather wet. Our people are all just watching the situation."