KEY POINTS:
Leave the electric blankets and gas heaters in the cupboards - New Zealand's Indian Summer is likely to drag on into winter.
Though Queen's Birthday weekend was cooler, with skifields welcoming the snowfall, the country has just bathed in the warmest May in more than 140 years of temperature measurements.
Most of the nation also experienced the driest May on record and enjoyed more sun than the average autumn.
And scientists from the National Institute of Water and Atmospheric Research say there is little sign of a cold snap in the next couple of months.
Niwa principal scientist Jim Salinger said it was difficult to say whether the balmy weather was a result of climate change, but said winters around the world were averaging a degree Celsius warmer than a century ago.
"May produced a truly Indian Summer. The Tasman Sea has warmed up and temperatures are expected to be above average for much of the country in June and July, so there's no hurry to get the heaters and blankets out just yet."
The national average temperature for May was 12.4C - 1.7 degrees above normal, and the warmest since temperatures were first kept in the 1860s.
Dr Salinger said the mercury was prevented from dropping by warmer than normal seas to the west of New Zealand and anticyclones to the east producing warm north westerlies over the country.
The highest temperature was recorded on the first day of the month, at Whangarei Airport, where it peaked at 24.8 C.
Much of the country has also enjoyed glorious sunshine, with the number of sunshine hours up 150 per cent on the usual.
That has kept the rain clouds at bay with a fraction of the normal rain for May. Most of the North Island has seen between a quarter and a half the normal amount of rain fall, while in the South Island there has been as much as three-quarters less than normal.
And while many people have been able to get out and enjoy the weather, it's been bad news for farmers in the Hawke's Bay. Many have been forced to sell stock due to insufficient feed for winter and more special drought sales are planned this week.
The anomalies were parts of Nelson and Taranaki, which were flooded when heavy rain fell over May 22 and 23. Torrents of water washed down Nelson streets, closing schools and a supermarket and forcing some people to evacuate their homes.
Four houses were flooded along the Taranaki coast and a car was swept downstream and out to sea. Elsewhere, thigh-deep water flooded a motel in New Plymouth and water was knee-deep in other parts of the city.
But they were the exceptions. Dunedin was the driest of the four main centres, Auckland the warmest and Christchurch the sunniest.
The unusual spell has been mirrored across the Tasman, with Australia recording its equal warmest May on record, at 2C above normal.
In New Zealand, it has meant fewer people cranking up the heating. Average daily power demand in May was 4.3 per cent less than a year earlier. Energy use reached a record last June when early winter storms brought snow to much of the South Island and caused blackouts in parts of Auckland.
Niwa climatologist Stuart Burgess said there was little chance of that happening again.
"Temperatures are expected to be above average in most regions and near or above average in the north of the North Island."
But a slight drop in temperatures over the last few days is good news for snow-lovers.
The South Island's Coronet and Mt Hutt skifields are set to open on Saturday, while Mt Ruapehu, in the North Island, is due to open a week later, on June 16. Marketing manager Mike Smith said there had been "snow dances and burning of old skis" as superstitious rituals to encourage snow to fall.
"We will make a final call two or three days before the scheduled start day, but with snow forecast everyday this week and the snow making system we have, we are very hopeful of getting going."
