"Although the loss of the high means we are likely to see wetter conditions at some stage over the weekend, it isn't all bad news as the return of milder air over New Zealand will give respite from those cold, frosty mornings," Mr Law said.
"The stubborn nature of the rain over the ranges of Westland could result in some high rainfall totals there over the next few days."
Although the heaviest rainfall was forecast about the main divide, some was expected to spill over the Southern Alps into the headwaters of the lakes and rivers of Canterbury.
Northwest winds and light showers were expected for the All Blacks and the Black Ferns' games in Auckland tomorrow, Mr Law said.
Meanwhile, the shortest day of the year - the day with the least amount of sunshine - is just over two weeks away now.
The June winter solstice will happen on Saturday June 21st just before 11pm.
On that day, sunlight will shine roughly for 9 hours and 30 minutes across New Zealand, compared to about 14 hours and 30 minutes on the longest day of the year just before Christmas, WeatherWatch.co.nz said.
"With the long nights we can expect lower temperatures when we wake up for the next couple of months - with frosts especially likely with clear nights," analyst Philip Duncan said.
Main centre weekend forecasts:
* Auckland - tomorrow, cloudy periods, with a few showers. Northeasterlies. Sunday, cloud increasing, rain developing. Northeasterlies freshening.
* Hamilton - tomorrow, mostly sunny. Light winds. Sunday, becoming cloudy, scattered rain later. Northeasterlies developing.
* Wellington - tomorrow, often cloudy, with a few showers mainly in the morning. Fresh northerlies. Sunday, cloud increasing. Northerlies dying out.
* Christchurch - tomorrow, cloudy periods. Light winds. Sunday, rain developing. Winds mainly light.
* Dunedin - tomorrow, cloudy periods. Light winds. Sunday, rain and easterlies developing.
Source: MetService