Thunderstorms and sun - NZ's volatile spring weather

A tree blown down by a sudden wind gust smashed this dinghy near Lake Taupo as Auckland and Taranaki braced for thunderstorms last night. Photo / Supplied

Northland, northern Auckland and Taranaki were bracing for thunderstorms, high winds and possible flight disruptions last night, as much of the rest of the country basked in sunny spring weather.

Air New Zealand warned that some flights in the upper North Island might be affected by forecast winds of more than 110km/h.

"Affected customers who would now like to delay their travel are encouraged to contact the airline at a later date to make these arrangements, rather than calling the contact centre during what's anticipated to be a very busy period," the airline said.

MetService forecaster Tom Adams said severe thunderstorms and wind gusts were expected across the upper North Island west of Tauranga and from Taranaki north.

However, the only damage reported by early evening was a dinghy smashed by a falling tree near Whakaipo Bay on Lake Taupo. Matthew and Michelle Whitbread-Edwards said a strong wind gust brought the tree down on top of their dinghy just after 2pm.

"We heard this big wind come through and then next minute this huge crash," Michelle said.

The gust also took out the power line to the family's water tank. The wind blew though quickly and eased.

Weatherwatch analyst Philip Duncan said isolated thunderstorms and associated wind gusts hit parts of Northland and Whangaparaoa in the early evening but blew over in less than an hour. He expected only temporary effects on aircraft.

"I wouldn't imagine anything big because those thunderstorms are moving around," he said. "Some of the flights will be manoeuvring around them a little bit. That might add a 15- or 20-minute delay in Auckland, and maybe New Plymouth and Hamilton."

Meanwhile Hawke's Bay and other parts of the southern North Island enjoyed sunny spells yesterday, drawing school holiday crowds to local playgrounds.

The MetService said strong winds would continue this morningwith the chance of more thunderstorms, clearing by this evening.