Mt Hutt ski area manager James McKenzie says milder temperatures will not make "huge difference" to the ski season.

Temperatures are picked to be up to 2 degrees Celsius higher on average this month, threatening weather records.

Weather forecasters say it could be a slow start to the ski season with unusually warm temperatures predicted across the country for much of May.

MetService forecaster Georgina Griffiths said the extended warm, dry spell was due to persistent high-pressure systems blocking to the east. That enabled very mild northerly winds to continue blowing from the north down the country.

JOSEPH JOHNSON/STUFF The leaves are falling but it still feels like summer in most parts of New Zealand.

The block was likely to be a major feature during the rest of May, although next week there were signs of a rain-bearing low pressure system heading this way. It was possible the last week of the month might bring rain.

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"The May forecast is extremely warm. In some places temperature anomalies for the month look between 1.5 and 2 degrees Celsius higher as an average for the month. If these predictions are correct, we could be close to having record warmth for May," Griffiths said.

Charlotte Curd/Fairfax NZ Manganui Ski Area in its prime during the winter of 2015.

"June will be the key month. If we don't start to see southerlies coming out of the southern ocean then, then we might not have a proper winter this year."

Surfers were making the most of the warmer temperatures, with Scarborough's Hannah Wilson saying the fine weather was an incentive to keep hitting the waves.

"When it's a bluebird [coloured sky] day of course you are going to want to out there compared to when it's just clouds and you can't see."

The extended dry spell was not good news for farmers though, especially after a tough summer.

Farmer Dan Hodgen, of Hawarden in North Canterbury, said they had experienced severe feed shortages after drought-like conditions in January.

"The warmth is positive because there is a reduced need for feed but we need some rain at some point otherwise are not going to grow grass."

Rangiora farmer Richard Smith said it was one of the driest autumns he could remember in his 30 years of farming.

"It's not as bad here because we do have irrigation . . . but the fact that we are irrigating at this time of year is practically unheard of."

National Institute of Water and Atmospheric Research forecaster Chris Brandolino​ said some temperature records could fall over the next week to 10 days.

"Our seasonal climate outlook for the whole country says warmer than average for the three-month period May-June-July. That doesn't mean there won't be cold snaps or frosts.

"People can save money on their power bill but it could be a slow start to the ski season."

Blue Skies Weather forecaster Tony Trewinnard​ said there was little doubt this month would be warm, although he expected rainy conditions might return later in May or next month.

"The Southern Ocean south of New Zealand is significantly colder now and will likely stay that way through the winter. That means when cold southerlies do arrive, and they will eventually, they could be colder than normal – snow-producing southerlies."

Mt Hutt ski area manager James McKenzie said milder temperatures over the next couple of weeks would not make a "huge difference" to the ski season.

"The key thing will be if we get the precipitation. Temperature-wise we're fine. We're certainly not concerned at this stage."



Porters Ski Area general manager Uli Dinsenbacher said with two months to go before the season opened, "anything can happen".

"We've had seasons before where we've had mild temperatures in April and May. It only needs one cold snap and one cold front and it changes all that."