Air New Zealand is experiencing its busiest winter school holidays on record, with the number of New Zealanders travelling to international destinations up 25 per cent on five years ago.

Analysis of customers booked over the two-week winter school holiday found Australia remains the most popular destination, followed by the United States and Fiji, but with hot-spots Bali and Vietnam making the top 10 for the first time.

The airline said West Coasters and Southlanders are most likely to head to Rarotonga for their winter sun, while Brisbane is the most popular for Dunedinites and Cantabrians.

Fiji is the top choice for customers starting their trip from Auckland, Napier and Palmerston North.

The big exodus mirrors pre-holiday travel data from Stats NZ which shows in the four weeks to June 24 just on 10 per cent more Kiwis travelled overseas. Nearly 260,000 travelled in that period.

Fiji was up 31 per cent, Bali 26 per cent, China 21 per cent, Samoa 15 per cent, Thailand 7 per cent, Cook Islands 6 per cent, United States 5 per cent, Australia, 4 per cent and Britain 2 per cent.

Air New Zealand general manager customer experience Anita Hawthorne said the airline's analysis showed New Zealanders planned holidays in advance.

"While most of the world makes flight bookings on the weekend and around four weeks before departure, we've found Kiwis arrange holidays two to three months in advance, with the most popular time to book flights on our website Wednesday night at 8pm.

More than 20 per cent of customers heading overseas these school holidays booked their trip on a Wednesday, and 15 per cent redeemed Airpoints Dollars to pay for their flights.

The airline will operate 17 per cent more seats to Pacific Island destinations, and 45 per cent more seats to Hawaii and to Bali this school holiday period compared to last year.

Travel agents say when the weather gets cold and miserable bookings spike.

And although underlying air fares have been increasing this year, there are still good deals particularly as part of packages.

Data from the past four decades show the number of holidays overseas has grown from nearly five times from 247,000 a year to 1.1 million in 2016.

The rise of Asian countries for a growing number and proportion of Kiwi vacationers has been most spectacular.

According to the Statistics NZ figures, compiled by the Herald's Data Insights team, in 1979 10,241 Kiwis went to Asia, or just 4.10 per cent of all residents on holiday.

This soared to 187,720 in 2016 to nearly 17 per cent of all travellers as airlines have during the past decade in particular poured capacity into the Asian nations and New Zealanders' taste for them grows.

Equally dramatic has been the slump in popularity for what was a Kiwi favourite, Britain.

The proportion making that big trek has plummeted from 8.3 per cent to 2.5 per cent.

And while Australia remains by far the most popular spot to visit with 430,000 crossing the Tasman in 2016, as a percentage of all outbound holiday travel it has shrunk from just over half to 38.7 per cent.

Travel experts say the holiday exodus has gained momentum that is hard to see slowing soon.

Kiwis aren't the only ones travelling in record numbers. In 2016 more than 1.2 billion people took overseas trips, according to United Nations figures, and they spent more than $1.7 trillion.

Many New Zealand travellers can afford it as the cost of air fares which are now at times a fraction of what they were 40 years ago. Improving aircraft efficiency, stable fuel prices over the past two years and cut-throat competition between airlines are keeping those fares low.

In 1983 an economy-class return fare to Los Angeles was $2196 or close to $5000 when adjusted for inflation. Some LA fares have dropped below $800 over the past two years as more airlines fly directly across the Pacific, more than doubling the number of New Zealand travellers over six years.

A Statistics NZ international air fare index dating back to 1981 shows fares climbed to their highest point five years later but as of last year fell to levels near those when it was started.