The company's general manager of sales and marketing, Craig Douglas, said ski operators were prepared for changed weather patterns and snow-making machines needed only cold temperatures.
"The little bit of work that's been done on it by the academics has suggested that we're not going to be significantly temperature-affected by global warming in our particular locations," he said.
In the shorter term, the company relied on five-day forecasting.
"We don't have long-term trend forecasting, We have to deal with a tremendous amount of variation which is far more important than any long-term trend."
This means spending millions of dollars peppering snow-makers and installing water and air pipes around the fields. The machines work at temperatures around -2C and ensure the main trails are kept open.
On Coronet Peak there are 200 of them.
"Our business is about snow and the big issue is about reliability - to be able to go to the market and be able to say this will happen," Douglas said.
Coronet Peak and Mt Hutt are scheduled to open on June 7 and The Remarkables a fortnight later to coincide with the Queenstown Winter Festival.
NZSki is owned by Trojan Holdings, whose owner is South Island tourism pioneer and investor Sir John Davies, a former mayor of Queenstown.
Anderson said the business had elements of risk around it, but was making good returns.
"It's heavily capital intensive so you do have to have ambition and guts."
He said NZSki had about 35 per cent of the market and its fields had just on 500,000 visits a year.
This winter was shaping up strongly from Australia, whose skiers are the biggest spenders and make up about half the number who hit the slopes at the Queenstown fields.
Airlines this winter will have 50 direct transtasman flights - up 10 a week on last year.
Douglas said that while Australia was not in the best economic shape domestically, as a market of origin, it was lining up positively.
"The value for money that was offered by the North American market and the Euro [zone] has largely been diminished by currency movements there. People were doing a lot more long-haul but now maybe they'll travel closer to home."
Rules restricting flights from the airport to daylight could be relaxed as early as winter 2016 which would boost tourism further, Douglas said.
Opening up
Conditions permitting
• Mt Hutt, Coronet Peak - June 7
• The Remarkables - June 21
• Mt Ruapehu ski areas - June 28.