Finance Minister Bill English now believes the drought could cost the nation's economy up to $2 billion - double the figure estimated last week.
"The latest advice is that somewhere between $1 billion and $2 billion will be knocked off our national income, and as every week goes by, the prospect of it being $2 billion instead of $1 billion grows,'' he told TVNZ's Q + A programme.
Mr English further warned that the drought could potentially knock 30 per cent off New Zealand's growth rate in a year.
"This underlines for us the importance of our primary production sector,'' he said.
Weatherwatch analyst Richard Green said most of the drought-stricken North Island, and much of the South, got a reasonable soaking overnight and this morning.
It was the most rain the country had seen since the first week of February. However, it was not a "drought breaker"
"Nonetheless, it will make places greener and top-up water tanks,'' Mr Green said.
"It's looking like coming and going this afternoon and tonight and that will continue tomorrow New Zealand-wide, by the looks of things."
Federated Farmers president Bruce Wills said the rain would give farmers hope.
"Probably the best thing from farmers' point of view is the weather's been very settled until now with anti-cyclone after anti-cyclone drifting across the country. What's giving farmers hope is there is quite a distinct change in the pattern now."
While farmers who received 5 - 10mm of rain would still be very much in drought, their spirits would be lifted.
"All it'll do is bring some hope and wash some dust off some leaves. It won't be enough for good grass growth but at least it's a start and it'll start softening up the soil."
Most of the North Island had received 5-10mm of rain so far, with Kauri near Whangarei getting the most rain in the country, 15mm.
Unusually, the driest part of New Zealand today was Southland. Gisborne and northern Hawkes Bay also hadn't had rain yet.
The heaviest showers brought by this system would in the upper South Island late tonight, while the central North Island would continue to get moderate falls.
The upper North Island would likely have further intermittent rain today and tomorrow.
The low currently over the country should remain here until Tuesday, when an anti-cyclone was forecast to arrive and bring back the dry weather.
This should stay until Friday, when there could be more rain.
Mr Green said the North Island needed 70 - 100mm of rain in order to break the drought.
"But we don't want that all at once because the ground is so hard it would run off and create flooding. Ideally, we would like close to 100mm of rain over two to three weeks."
WeatherWatch's Philip Duncan said the drought was now the worst in three decades.
(as at 5.30pm)
Upper and central North Island
(Northland, Auckland, Coromandel, Waikato, Waitomo, Taumararnui, Taupo, Bay of Plenty, Taranaki)
15 - 30mm
Note, 60 - 80mm of rain fell on the upper slopes of Mt Taranaki.
Lower and eastern North Island
(Wanganui, Taihape, Manawatu, Horowhenua Kapiti, Wellington, Wairarapa, Hawkes Bay and Gisborne)
0 - 5mm
Nelson, Buller, Westland
15 - 25mm
Note, 50 - 100mm of rain fell in the Southern Alps and western ranges of Nelson.
5 - 15mm
10 - 30mm
Note 40 - 60mm of rain fell in the Otago headwaters.
Canterbury and Marlborough
0 - 5mm
Note 15 - 30mm fell in the MacKenzie Basin and northern ranges of Marlborough.
- Source: Metservice