Flights have been grounded at Dunedin Airport and Portobello Rd is flooded due to strong winds this afternoon.
A police spokeswoman said "surface flooding'' on Portobello Rd was caused by a combination of winds and a high tide.
The Otago Daily Times has received reports of two motorcyclists crashing on the same road due to strong wind gusts.
The spokeswoman was working to confirm this.
Surface flooding was hampering drivers on State Highway 6 from Lake Hayes to Queenstown, parts of the Lindis Pass and low-lying side streets in Alexandra, she said.
Airport marketing and communications manager Megan Crawford confirmed flights had been cancelled and delayed.
Airport staff were monitoring the situation, she said.
An Air New Zealand spokeswoman said NZ5053 from Christchurch to Dunedin returned to Christchurch and this caused the cancellation of the return flight while NZ5327 from Wellington to Dunedin returned to Wellington causing the cancellation of that return flight.
Flight NZ5391 from Wellington to Dunedin was diverted to Christchurch, causing the cancellation of that return flight.
Flight NZ5394 Dunedin to Christchurch had also been delayed, she said.
For up to date flight infomation, people should check the Air NZ website, the spokeswoman said.
Motorists in the South Island have been warned to take extra care on the roads due to high winds.
Police said there had been two incidents of vehicles rolling, with high winds suspected to be a contributing factor.
A trailer overturned on State Highway 73 on the Springfield to West Coast Road. A recovery vehicle is attending and drivers are advised to avoid the area if possible.
On State Highway 79, on the Geraldine to Fairlie Highway, a campervan rolled.
In both incidents no injuries were reported.
High winds blew over a caravan on State Highway 85 between Ranfurly and Omakau about 11am.
Nobody was injured, but one lane of the highway was blocked for a short time.
Millers Flat lost electricity about 1.20pm, and it was restored after about an hour and a half.
Strong winds lashing central New Zealand this afternoon are forecast to intensify this evening.
North-westers are howling through Wellington, Kaikoura, Christchurch and Southland.
Philip Duncan of Weatherwatch.co.nz said 90km/h gusts were recorded this afternoon.
Wellington had a wild night last night and a fallen window pane closed busy inner-city road The Terrace this morning.
After a time of calm, the wind is picking up again but Mr Duncan said the 140km/h highs will probably strike the mountain and hill areas.
A blast of strong to gale force westerlies is moving in and May last for a week or longer in some areas.
The new weather pattern sees an end to the subtropical airflow and wetter weather for the west bit warm, windy and dry in the east. The weather over the next week may prompt a few weather warnings Video
"It's most likely we'll see it in extreme places, more higher up and exposed coastal areas," he said.
In Wellington city, gusts could reach 120km/h, which could cause damage and break branches.
"Wellington's pretty good at dealing with that. They haven't had much of that this year. Wellington's had the most incredible summer that's going on forever," Mr Duncan said.
"The winds are going to crank up a bit as we go through today and tonight. It comes in in big surges.
"It's pretty much non-stop coming in from the same direction."
Mr Duncan said the surges were like waves crashing into a beach. There would be periods of calm and then they would start again.
He expected the winds to move away from Canterbury during the evening and instead hit areas around the Cook Strait. Tomorrow is expected to be calmer but more wind is expected over the next few days for central areas.
This morning, fire crews were called to Carterton and Tauherenikau in Wairarapa after a shortlived burst of high winds twice caused power lines to arc, cutting power to more than 1500 homes.
Powerco asked Wairarapa people to secure objects that could blow into overhead power lines as the severe winds picked up.
Power was cut to more than 1490 properties in the Carterton suburb of Carrington just before 9am but was mostly restored by 9.30am.
In Greytown's Morrisons Bush, power was cut to 230 customers at about 7.50am.
MetService this morning extended its wind warning to include central Hawkes Bay, and 140km/h gusts were expected to lash the eastern coastline of both islands today.
MetService says small tornadoes were possible in coastal areas.
More heavy rain is expected to fall on already deluged western areas of the South Island and Southern Alps.
MetService has this afternoon issued a thunderstorm warning for Westland, Selwyn and Ashburton.
There is also a heavy rain warning for the Tararua Ranges north of Wellington.
West Coast Civil and regional council are monitoring local rivers.
The Waiho River that breached its banks in Franz Josef in March is not causing concern but a stretch of State Highway 67 north of Westport remains closed because of flooding.
The road between Hector and Lamplough is impassable because of flooding and debris. No detours are in place.
The New Zealand Transport Agency is also cautioning drivers using the highway north of Westport to Mokihinui to beware of surface flooding.
The agency also issued a strong wind warning for motorists using the Rimutaka Hill today. They asked those on motorbikes or in high-sided vehicles to take care.
In Christchurch, authorities are urging high-sided vehicles and motorcyclists to take care as a high wind warning has been issued.
Wind warnings have been lifted on SH80, Mt Cook to Twizel; SH79, Fairlie to Rangitata; and SH8, Twizel to Timaru.
A strong-wind warning remains in place on SH1, Kaikoura to Blenheim.
