Much of the country is in for rain today with a few places expected to remain untouched by showers.
MetService meteorologist Mmathapelo Makgabutlane said an active front would continue northwards across the lower South Island today, bringing rain.
A heavy rain warning is in force for northern Fiordland, the ranges of southern and central Westland, and the Otago headwaters.
"[In the western parts] for the duration of the heavy rain event, which will have started very late last night, we are expecting rainfall amounts in the region of about 80-120mm," Makgabutlane said.
That should be the worst of it, she said.
After days of sun the City of Sails will start to cloud over today with the chance of showers.
"There is also the possibility of some thunderstorm activity mainly in Northland and then the Auckland region - mainly north of the city," Makgabutlane said.
Rain and showers continue across the country tomorrow, with the South Island again predicted to bear the brunt.
In Auckland, stronger winds are expected to develop by Tuesday, with gusty northwesterlies amid heavier rain.
By Wednesday, Auckland is expected to be partly cloudy with a few showers clearing in the afternoon or evening.
Forecaster, WeatherWatch.co.nz said it was the first prediction of "soaking rains in several weeks" and for many farmers and growers this is "definitely an early Christmas present".
"The month of November was much warmer and much drier for the top and east of the North Island with mid-summer temperatures burning off moisture before summer had even arrived.
"The rain this week will allow farmers, growers and those who rely on rain water to perhaps sleep a little easier at Christmas time and heading into the start of the new year."
Will NZ get enough rain?
"Rainfall totals do vary due to our mountains and ranges and yes, some people may miss out on a true soaking into the soil," the forecaster continued.
But many places should get some nice rainfall.
"Totals are not high for everyone - this doesn't appear to be a single rain event that reverses the big dry that has formed. Some parts of Waikato, for example, only have 20 to 30mm forecast in total from this event.
"That is very welcome rain but no way near enough to make up for the deficit. Other areas in the hills or more north facing into the rain bands may get 50 to 100mm."
Main centre forecasts today
Showers developing in the morning, chance heavy and thundery from afternoon. Northwesterly breezes. High 25C, low 17C
Clouding up, chance morning shower. Then showers afternoon and evening, chance heavy, and possibly thundery in the north. Northwest breezes. 23C, 17C
Becoming cloudy this morning. Chance of a shower, mainly from afternoon. Westerlies gradually turning northerly. 23C, 15C
Becoming cloudy this morning. Chance of a shower, mainly from afternoon. Westerlies gradually turning northerly. 24C, 17C
Fine with high cloud. A few showers at night. Northerlies, picking up from afternoon. 18C, 15C
High cloud and northerlies. A few showers, chance heavy, with a late evening southerly change. 25C, 11C
Rain developing morning, possibly heavy, clearing afternoon to fine spells. Southerlies developing morning, easing evening. 17C, 10C