Steady rain is falling across Northland and Auckland this afternoon with winds continuing to build. Winds are averaging 100kmh in the Hauraki Gulf with gusts to 111kmh in the past hour.

In Auckland winds are gradually building, especially in northern, eastern and central areas.

Gusts are close to 70kmh for suburbs along the eastern coastline and are nearing gale force as the afternoon continues.

While it remained relatively calm in Auckland this morning, winds are expected to pick up by afternoon with predicting gales in the North Shore, east coast suburbs and other exposed areas either late today or overnight.

Forecasters today also said driving conditions were likely to be hazardous and outdoor activities disrupted.

Surface flooding could be expected, as well as slips, rapidly rising stream and rivers, and damage to trees and buildings.

The MetService said heavy rain and damaging winds were forecast to affect areas from Northland to Waikato and across to Bay of Plenty and Gisborne over the weekend.

Heavy rain was likely to spread south today, before easing in most places from tomorrow afternoon.

Up to 150mm of rain was possible in Northland, especially about the eastern hills from Whangarei northwards. About 120mm was expected to fall in the Auckland region, the Coromandel Peninsula and the Kaimai Range.

The heavy rain was predicted to hit the Gisborne area from tonight through to midday Monday, with readings of up to 150mm forecast. The rain would be accompanied by gale force easterlies, with gusts expected to reach 140kmh today and tomorrow. head weather analyst Philip Duncan warned people to prepare for power cuts and other disruptions. "We're not wanting to alarm people," he said.

"This is a moderate storm, but people should be prepared for power cuts and the potential for some damage."