Flu consultations are way below average this winter but health experts warn the worst could be yet to come.

District Health Boards have recorded a 76 per cent drop in consultations for influenza-like illness [ILI] this year compared to the seasonal average.

This year's winter has been unusually warm, with record temperatures even triggering an explosion in the bug population, as more wasps, flies and mosquitoes survive the colder months.

The Ministry of Health said it was too early to tell if the lower consultation rate could be attributed to milder weather.

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"Winter has only just started, and influenza levels may rise in July, August or September, as they have done in some previous years," a ministry spokeswoman said.

In 2009 ILI rates were also well below seasonal average, running up to May, only for a huge spike to send consultation levels close to 300 per 100,000 people in July.

The average over the past five years has been 72.2 consultations per 100,000.

"While this year has been mild to date, we haven't had a huge reduction in influenza rates, which varies from year to year, " the spokeswoman said.

"Influenza vaccine continues to be available free to eligible people until the end of August, because of this possibility."

Increased vaccinations are also likely to have played a role in this year's numbers.

As of the start of July 2016, more than 1.2 million doses of flu vaccine had been distributed.

Those seven-month statistics equal full-year statistics for the past three years.

Health Minister Jonathan Coleman this month said the seasonal flu immunisation programme was being extended to the end of August.

"While we've had great uptake of the influenza vaccine this year, there may be people who haven't got around to getting immunised," he said.

"Ministry of Health surveillance data suggests that influenza rates have not yet peaked this winter.

"However, if levels start to increase in late winter as they did last year, it's important that people can still access the vaccine."

The influenza vaccine is free for people 65 and over, pregnant women, people with long-term health conditions such as severe asthma, and children under 5 who have been hospitalised for a respiratory illness.

The warmer weather that may be staving off flu is likely to continue.

"It doesn't mean there won't be cold snaps, but we think temperatures are very likely to be warmer than average for the remainder of winter and beginning of spring, for all of New Zealand," Niwa principal scientist Chris Brandolino said.