Bay's unusually warm autumn a record breaker

If you were thinking things have become suddenly much cooler than what they were, official weather records will prove you right.

Despite today's cold snap in Tauranga, Metservice has confirmed the city has experienced its warmest autumn since records began in 1913, with last month was the warmest May ever.

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.

It was the warmest May on record for five of the six main centres. Dunedin observing its third warmest May.

However, a cold snap last week meant Tauranga experienced it's coldest morning so far this year on May 24 with a temperature of 6.9C being recorded at Tauranga Airport.

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 stated 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 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 flop-flop between dry and wet phases.

Niwa National Climate Centre principal scientist Chris Brandolino said 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.

"It's one of the warmest years on the planet," he said.