Downpours around the country will have passed by New Year's Eve, but most of the North Island can expect a damp holiday and the Mount could still get another dousing.
MetService weather ambassador Bob McDavitt says Cyclone Fina has collapsed north of New Zealand, but the moisture it was dragging behind it will create wet conditions for most of the country on Saturday and Sunday.
"That cyclone lost its top, blown to shreds once it hit the jetstream south of New Caledonia," he said. "But the low-pressure centre is still there, and that's where all the moisture comes from."
The most severe weather would strike tomorrow, particularly in Nelson. "Even campers and trekkers do need to go and see the movies eventually, and Friday looks like a movie day to me," said Mr McDavitt.
"The heavy rain should ease in Nelson on Saturday, but damp conditions are likely over much of the islands for New Year's Eve, and heavy rain is likely in the Bay of Plenty until New Year's Day."
Downpours are expected to begin tomorrow morning in the Bay of Plenty, and up to 100mm of rain could fall in the popular New Year's Eve destination of Mt Maunganui. The heavy rain is not expected to diminish until New Year's Day.
The plethora of outdoor festivals in the North Island are all likely to get rain at some stage, though the annual Rhythm and Vines in Gisborne should get only intermittent showers. It will also be warm - around 23C.
New drum'n'bass festival Northern Bass, in the Bay of Islands, could face heavy rain on Saturday while several Matakana events such as the Highlife New Year's Eve Experience are also likely to take place in overcast or wet conditions.
Mr McDavitt said it would be damp but not miserable in these holiday spots as winds would remain light and day temperatures would stay in the 20s.
New Zealand continues to warm up after a cool December, and Gisborne and Central Otago could hit 26C on New Year's Day as northerlies drag down warm air from the Pacific.
Far North/Bay of Islands: New Year's Eve: Periods of rain, possibly heavy, 23C. New Year's Day: Occasional rain, northerly winds, 24C.
Whangarei: NYE: Periods of rain, 23C. NYD: Rain, 24C.
Auckland: NYE: Periods of rain, possibly heavy, 23C. NYD: More rain, northeasterlies, 22C.
Bay of Plenty: NYE: Rain, possibly heavy, 23C. NYD: Periods of rain, possibly heavy, northerlies, 22C.
Gisborne: NYE: Occasional rain, light winds, 23C. NYD: Occasional rain, light winds, 25C.
Nelson: NYE: Periods of rain, light winds, 23C. NYD: Rain at times, light winds, 23C.
Canterbury: NYE: Rain in north, fine in south, northeasterlies, 21C. NYD: Showers and south-easterlies developing, 21C.
Central Otago: NYE: Fine, 24C. NYD: Fine, light winds, 25C.