The entire North Island and most of the South Island should be mostly dry tomorrow.
WeatherWatch said the South Island's West Coast would not be so balmy, and some "spillover spits" could fall on the east coast but the Mainland would otherwise avoid rain.
Things would get "a little more complicated" on Sunday, WeatherWatch said.
The northwestern South Island from around Greymouth to Nelson would probably be rainy, and patches of rain were possible in the North Island too, especially in the top half of Northland.
The same northeasterly flow responsible for those possible showers up north could dump rain on the western Bay of Plenty and on eastern Coromandel peninsula holiday hotspots.
In a weather move reminiscent of a "no surprises" policy, rain would also return to perennially-damp Fiordland, this long weekend's wettest region.
Most of the country would moisten on Monday.
"Monday seems to get wetter by the hour as a slow moving cold front heads towards towards New Zealand from the west," WeatherWatch said.
The South Island's west side would stay wet with spillover rain forecast for Southland and western Otago.
Showers, possibly heavy, were possible around Nelson and Marlborough.
At least half of the North Island could experience rain or showers but WeatherWatch said people could still expect plenty of dry areas across the country. The dry spots could get a bit more cloudy and windy as the long weekend drew to a close.
WeatherWatch said people planning to extend their break to Tuesday should watch out for heavy rain in both islands and isolated thunderstorms as a new low pressure system moved in.
Your upper North Island forecast for Queen's Birthday weekend:
SATURDAY
Whangarei: Fine breaks and the odd shower with northeasterlies. High 17C, low 12C
Auckland: Fine with northeasterlies. High 17C, low 12C
Tauranga: Mainly fine with a chance morning and evening showers; northeasterlies. High 16C, 11C
Hamilton: Fine with light winds. High 16C, low 6C
SUNDAY
Whangarei: Rain developing in the morning with a chance of heavy falls; northeasterlies. High 18C, low 11C
Auckland: Cloudy periods with a few showers, and rain in the evening; northeasterlies. High 17C, low 12C
Tauranga: Cloudy periods and a few showers with northeasterlies. High 17C, low 12C
Hamilton: Cloud increasing with evening rain and northeasterlies developing. High 17C, low 9C
MONDAY
Whangarei: Rain easing to showers in the morning, with northerlies. High 19C, low 13C
Auckland: Rain easing to a few showers in the morning, with northerlies. High 17C, low 14C
Tauranga: Rain at times with northeasterlies freshening. High 17C, low 13C
Hamilton: Occasional rain, easing later, with northeasterlies. High 17C, low 10C
(Source: MetService)