The South Island meanwhile was not looking too bad for Friday, with just some areas of fog and isolated showers on the West Coast.
Tonight there was a good chance of fog for much of the country ahead of mostly settled weather tomorrow, Dyason said.
On Sunday a deep low would arrive from the Tasman Sea in the afternoon and evening, bringing rain - at times heavy - to much of the country's west coast.
While the North Island would see a burst of rain, the heaviest falls were expected for the South Island's West Coast.
There was a moderate confidence rainfall reaching warning criteria (100mm in 24 hours) over western and northern parts of the South Island, along with a low chance for Mt Taranaki.
Northerly gales could also become severe from Auckland to Whanganui across Taupō and Bay of Plenty, also Wellington, Wairarapa and northern Marlborough.
The front would be followed by a ridge of high pressure on Monday. On Tuesday, a cold front should move on to the south of the South Island from the southwest.
Today's weather
Whangārei
Rain at times, clearing by evening. Northerly breezes. 22C high, 12C overnight.
Auckland
Fine spells and chance late shower. Northerlies. 21C high, 12C overnight.
Hamilton
Morning rain then fine spells and chance shower. Westerlies dying out at night and fog developing. 21C high, 9C overnight.
Tauranga
Showers, clearing to fine spells in the afternoon. Northerlies dying out. 21C high, 11C overnight.
New Plymouth Early rain, then fine spells and chance shower. Northwest breezes. 19C high, 12C overnight.
Napier Light morning rain possible then becoming fine. Northerlies turning westerly in the evening. 24C high, 8C overnight.
Whanganui Early rain, then fine spells and chance shower. Northwesterlies. 21C high, 12C overnight.
Wellington Cloudy with a shower or two. Clearing to fine in the afternoon. Northerlies, strong at first. 18C high, 14C overnight.
Nelson Early rain, then fine. Northerlies, dying out evening. 19C high, 10C overnight.
Christchurch Fine. Light winds. 20C high, 7C overnight.
Dunedin Fine, some evening cloud. Light winds. 19C high, 10C overnight.
