Tauranga had its warmest autumn on record last month.
Despite yesterday's cold snap in Tauranga, the MetService confirmed the city had its warmest autumn since records began in 1913.
In the MetService's rural outlook, it said May had been extremely mild due to the combination of frequent northwesterlies and warmer than usual seas around the country.
The first half of the month was exceptionally warm and even with a wintry end to the month, many new May temperature records were set around New Zealand.
MetService meteorologist Lisa Murray said the highest temperature for May this year was 22C, on May 3.
The warmest temperature in May of last year was 21C, she said.
The average temperature for May - calculated by recording temperatures every hour during the day and at night - was 15.5C. This was up from the average temperature for May in 2015, 12.7C.
Ms Murray said Tauranga had a normal amount of rain for the month.
It was the warmest May on record for five of the six main centres. Dunedin observed its third warmest May.
However, a cold snap last week meant Tauranga experienced its coldest morning so far this year on May 24, with a temperature of 6.9C being recorded at Tauranga Airport.
Temperatures at the airport reached as low at 6.5C about midnight yesterday.
MetService meteorologist Ciaran Doolin said while the morning's chill factor was no record breaker - Tauranga once reached an overnight low of 1.9C in 1994 - it was the coolest temperature of the year and had been a long time coming.
The outlook for June confirms an unusually cold and frosty start but well above average temperatures are expected to return next week.
The outlook states the monthly temperatures will likely end up on the warm side of the ledger, but overall, large temperature swings are expected in June.
Similarly, rainfall is forecast to swing widely from week to week.
The month starts out abnormally dry under high pressure, while next week looks very wet for most areas due to prevailing northerly winds.
The second half of the month also looks likely to flip-flop between dry and wet phases.
Last week, Niwa National Climate Centre principal scientist Chris Brandolino said that last week that Tauranga was on track to having the warmest May on record.
"What's been atypical is it hasn't gotten cold until recently. We've had pretty settled weather and warm weather. That was the unusual bit."
Mr Brandolino said climate change was no doubt part of the reason for the warm weather.
"It's one of the warmest years on the planet," he said.
Today: Fine, max 15C, low 6C
Friday: Fine, max 16C, low 6C
Saturday: Fine, max 16C, low 8C
Sunday: Fine, max 16C, low 8C