Dunedin Airport's website shows a slew of cancellations this morning and many flights in and out of Queenstown Airport have also been cancelled.
Transpower this morning said about 90,000 households were believed to be affected by the outage, but power was being restored by late morning.
The provided advised about 11am it had partially restored power to affected areas.
"Greymouth, Stoke, Blenheim, Culverden and Kaikōura have been reconnected to the national electricity grid, and local lines companies in those areas are in the process of supplying power in their respective networks.
"While the severe weather event continues, further outages are possible."
Marlborough Lines said about 10am that power was being restored across the region.
"We are gradually relivening the network and expect full restoration by 12pm. Please treat all lines as live at all times, especially if any lines have come down — stay well clear and report any hazards immediately."
Many businesses were forced to close due to the outage and some were operating cash only.
Transpower's executive general manager, Mark Ryall, earlier told Nine to Noon there were three big transmission circuits for the upper South Island which had all tripped.
Nelson City Council said the power outage included Nelson, Hanmer, Greymouth and Blenheim.
"Transpower crews are working to restore power. Traffic lights are out across the region, and motorists are being urged to drive with extra care."
Shortly before 10am the council said power was being restored throughout the city.
As power was being restored further north, more than 1600 people in the Hanmer Springs area were without supply around 11am.
The Hurunui District Council says trees have fallen across a powerline and multiple roads.
MainPower's website says it's aware of the outages and is working to restore supply.
Meanwhile, State Highway 7 from Hanmer Springs turnoff to Springs Junction is closed due to flooding.
Power is also out to thousands of customers in parts of the North Island.
Gusts of more than 200kmh were recorded overnight in exposed areas of the Canterbury High Country already, and more strong winds are expected to hit the wider region and lower North Island today.
A red wind warning is in place in Wellington, Christchurch, wider Canterbury and Marlborough from Cape Campbell southwards.
MetService head of weather news Heather Keats says pretty much all of the eastern side of the country will get strong winds today.
Flights cancelled
At Christchurch Airport at least 55 cancellations are listed on its website, while Air New Zealand has cancelled all flights out of Wellington Airport this morning, after its website earlier showed 67 cancellations.
The airline said travellers booked on flights between 6am and 6pm could change their bookings free of charge to any time within 48 hours of their original flight. Changes can be made directly through the Air NZ app.
Several highways are closed in both main islands, owing to surface flooding, slips and trees coming down.
'Threat to life'
Keats from MetService told Morning Report today's destructive weather would impact all of the South Island and most of the lower North Island.
She said the warnings should not be ignored and there was a threat to life.
"It's set to ramp up from now and only going to get worse."
Keats said the weather system was fast moving so it should improve later today, but more bad weather would return on Monday.
Despite the bad weather, there would be unusual heat, with Hastings reaching 30 degrees Celsius.
"This spring has been relentless," Keats said.
"It does feel like it has been system after system after system."
Keats said the stronger winds this week were more than MetService would usually expect to see in spring.
Raft of warnings
MetService late last night issued warnings for "potentially destructive and damaging winds" across southern regions today.
The forecaster is advising residents to "stay indoors or seek sturdy shelter away from trees".
MetService meteorologist Mmathapelo Makgabutlane said Otago, Southland and Canterbury had already had "one big windy system" this week, but this one was expected to be more intense.
She said the severe gales were caused by a deep low-pressure system to the south of New Zealand, and a high-pressure system to the northeast of New Zealand.
"That difference in pressure between the low-pressure and the high-pressure systems will be really intensifying the winds, especially because they’re in such close proximity, and that low is quite low — possibly lower than 960 hectopascals.
MetService this morning issued a fresh round of severe weather alerts, updating its red warning for strong winds in the Canterbury High Country from 9am to 5pm today. Emergency Management and Recovery Minister Mark Mitchell yesterday declared a state of emergency in the region.
"I have made this declaration as the Canterbury mayors have not yet been able to be sworn in following the recent local elections," Mr Mitchell said.
"The National Emergency Management Agency have been in close contact with the Canterbury Civil Defence Emergency Management Group and confirmed that a declaration is necessary.
"The state of local emergency will ensure local Civil Defence have access to the emergency powers they need to respond and support emergency services during this event."
Orange wind warnings have also been updated for Otago, Southland and Stewart Island from 9am to 3pm today, and for Dunedin and inland parts of Clutha and Southland from 9am to 4pm.
There was a chance of those being upgraded to red warnings.
Those in red warning areas could expect severe gale northwesterlies with damaging gusts of up to 150kmh in exposed places.
A heavy rain warning for the headwaters of the Otago lakes and rivers was due to lapse at midday.
Ms Makgabutlanesaid there would be threat to life from flying items and falling trees, and destructive winds would cause widespread damage, including powerlines and roofs.
It would also create dangerous driving conditions and significant disruption to transport and power supplies, so she urged people to stay indoors or seek sturdy shelter away from trees, and avoid travel.
"Also be ready for power and communication outages.
"If you still have power, charge your phones now in case the power goes out."
Those in orange warning areas could get wind gusts up to 130kmh. She said people should avoid driving high-sided vehicles or motorcycles.
The forecast for tomorrow is for showers in the west and south, with possible thunderstorms for coastal Southland and Fiordland, but it will be mainly fine elsewhere.
john.lewis@odt.co.nz/additional reporting RNZ
