Motorists are being warned not to take State Highway 2 over the Rimutaka Hill Rd because of the danger posed by high winds.
Police central communications inspector Marty Parker said there were two separate crashes about 1pm near the Upper Hutt side of the summit, which were likely caused by the wind.
A motorcyclist was blown from his bike and a caravan towed by a car had rolled onto its side, Mr Parker said.
No one was injured in either crash.
"It's definitely not recommended for motorbikes, caravans and high sided vehicles. Take extreme caution."
Flights in and out of Wellington Airport had been affected by the gusts, spokesman Greg Thomas confirmed.
Mr Thomas said about ten domestic flights to and from Wellington had been cancelled or delayed today, though international travel had not been affected.
MetService recorded gusts of 105kmh at 4am at the airport, but these were down to 90kmh by 7.30am and 70kmh at about 3.30pm.
Roofs in Kilbirnie, Karori and Newtown have lifted as winds in excess of 130kmh continue to hammer Wellington hills this morning.
MetService meteorologist Dan Corbett said the active front that was moving across southern and central New Zealand had delivered 15,000 lightning strikes nationally in the past 24 hours.
But temperatures remained warm, with Wellington and Auckland only dropping to 19 degrees Celsius last night and Christchurch to 24.1C.
Wellington City Council spokesman Richard MacLean said there were reports of minor damage coming in from across the city.
Trees and fences were among the casualities so far.
''There have been reports of portaloos blown over. Hopefully nobody was inside.''
A tree had blocked Alexandra Rd, which was causing problems for tour buses trying to drive up Mt Victoria.
''This is an extremely windy day, but it's not one of those real big emergency days by any stretch of the imagination.
He advised people against going walking on the tracks in Mt Victoria.
''You're likely to be sconned by a pinecone or a branch.''
Cyclists or motorcylists should look to use an alternative mode of transport.
''It's gusting and it's dangerous for people on bikes.''
The strongest wind was at the top of Mt Cook, which recorded a 230kmh gust last night.
MetService forecaster Erick Brenstrum said winds at the top of the Rimutaka Hill reached 133kmh overnight.
Kelburn had gusts of 123kmh, but they had died down to 90kmh by this morning.
Wellington Airport experienced winds of 105kmh at 4am. They too were down to 90kmh by 7.30am.
The northwesterly winds would drop off this afternoon to about half to two-thirds of their 7.30am strength.
Tomorrow would still be windy, however.
Fire service shift manager Murray Dunbar said between 7.30am and 8am firefighters were called to secure roofs that had lifted in Karori and Kilbirnie.
Road signs in Kilbirnie were being damaged by wind this morning and at least one had to be removed.
The fire service was also called to wind-related call outs in Brooklyn and Kilbirnie last night.
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