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Hundreds of helicopters have been on call overnight to respond to unseasonal frosts threatening fruitgrowers' livelihoods, but there have been doubts there would be enough to meet the demand.
Frosts in recent days, normally unseen in November, have threatened to kill off fruit, such as grapes for wine grown in areas like Hawkes Bay, Marlborough and Central Otago.
Frosts as low as - 6degC were expected today in parts of both islands.
Metservice forecaster Ian Gall said the cold blast in recent days was very unusual coming so late in spring.
Snow fell to near sea level in Christchurch yesterday, which was a rare occurrence "at any stage ... even in midwinter".
"This system dug in deep, and brought air from very, very far south right across the country."
John Sinclair, of Marlborough Helicopters Limited, predicted there would be nowhere near enough helicopters to meet the demand for combating frost across the country.
There are about 670 of the aircraft nationwide.
Mr Sinclair's firm had two choppers at the ready overnight for local vineyards with the temperature expected to dip into the negatives.
Many other helicopters were expected to come into Marlborough from elsewhere in the country.
The helicopters take to the air when the temperature reaches zero, and use special thermometers in the aircraft to find the layer of warm air that sits above the cold air near ground level.
The motor-powered blades then blow warmer air down to mix with the cold air and stop the frost forming.
"We are moving around about walking pace and covering as much ground as we can. We might do two hours and then refuel as quickly as we can and do another two hours."
Mr Gall said there was no particular reason for the cold snap - "just the vagaries of the weather really".
It was good that people had been given good warning of the cold weather in a time sensitive for crops and young lambs.
