Wellington was also being battered by winds of up to 110 km/h.
"Through Wellington it is a classic squeeze of those northwesterlies around us between the mountains and the Cook Strait, and it's going to give us a fairly blustery end to the day here in the capital."
Things will get better throughout Monday, Mr Law said.
"It will be a bit of a windy old start to the day and we are going to find those start to ease off though for the likes of Wellington.
"Further south it looks like a much better day in terms of wind, but we are going to find it is fairly wet."
There were heavy rain warnings in place for Fiordland and Westland tomorrow, he said.
For the rest of the North Island things were looking slightly better, however he warned it could be a wet day for Mt Taranaki and the Tararua Ranges.
"They are ones to keep an eye on we could see some heavier rainfall in that area."
He said elsewhere it was a fairly wet day for the rest of the country.
"We are going to find an improving story on Monday but we are going to have some showers."
Auckland would have a wet start to the day and a blustery northwesterly, however the rain should clear off in the morning and make way for a better and brighter afternoon, Mr Law said.
Tomorrow's forecast:
Auckland -- Rain clears around midday, then fine. Northwesterly turns westerly. High 18C Low 9C
Hamilton -- Morning rain, then mainly fine. Northerly turns westerly. High 18C Low 6C
Tauranga -- Rain clears early afternoon, then fine. Northwesterly turns westerly. High 19C Low 9C
Wellington -- Early rain then mainly fine, chance of afternoon showers. Strong northwesterlies. High 16C Low 9C
Christchurch -- Fine gusty northwesterly, late southwesterly with a few showers. High 18C Low 4C
Dunedin -- Fine, then showers from afternoon with southwest change. High 16C Low 5C
(Source: MetService)