A strong wind warning has been issued for Auckland Harbour Bridge with looming thunderstorms set to sweep over the city in coming hours.
Electric storms packed with potentially destructive winds and hail are set to rumble across much of New Zealand today.
Waka Kotahi NZ Transport Agency has issued a strong wind warning in place over the bridge, advising motorists travelling this route to take extra care, especially if they are in a high-sided vehicle or riding a motorcycle.
MetService is warning the storms pose a threat to western parts of the North Island with damaging gusts of more than 110km/h, intense downpours and hail measuring up to 10mm.
The forecaster says Auckland can expect an afternoon of thunder and lightning with heavy rain, sqaully thunderstorms and powerful wind gusts of 90 km/h to sweep over the city.
The worst of the weather is forecast to hit between 2pm and 4pm.
Strong gusts of 83 km/h were recorded at Auckland Airport just after 2pm.
Lightning and thunder can be expected right across the day and into night from Raglan to Wellington.
MetService is warning the powerful gusts could be strong enough to damage trees, power lines and unsecured structures. The forecaster said driving might be hazardous, especially for high-sided vehicles and motorcycles.
Elsewhere across the country thunderstorms are expected to affect many parts of the South Island.
MetService said there was a moderate risk of thunderstorms hitting the West Coast, with hail up to 15mm during the rain storms and snow falling to 600m.
There was also a moderate risk of a few thunderstorms about inland parts of Southland, eastern Otago and South Canterbury this afternoon and evening, and parts of Canterbury and Banks Peninsula tonight.
MetService said these thunderstorms would be accompanied by brief heavy rain and hail, and for some areas, snow.
A heavy rain warning is now in force for central New Zealand with Buller, Canterbury High Country, Kāpiti-Horowhenua, Nelson, Tararua, Wairarapa and Westland.
A strong wind warning has been issued for central regions with gales expected to ramp up to 120km/h at times.
The rain is set to pour down from later tonight with intense falls during thunderstorms.
People were being warned the downpours could lead to streams and rivers rising rapidly.
Surface flooding and slips were also possible and driving conditions might be hazardous.
While Auckland escapes the worst of the thunderstorms, MetService says the region is in for a rainy afternoon with heavy falls at times. Strong northwesterly winds are expected to pick up around lunchtime and not ease until this evening.
The weather has already caused a traffic nightmare in the capital this morning with slips causing a derailment near Paekākāriki and forcing traffic on the nearby highway to a standstill.
Traffic has since started filing past the scene of today's dramatic derailment every 15 minutes.
Wellington Regional Emergency Management Office said a second slip had seen all train suspended on the Johnsonville Line after a slip came down on lines between Raroa and Johnsonville.
Motorists heading in and out of the capital have been advised to use the Paekākāriki Hill Rd.
Meanwhile, the South Island has received another round of snowfall today.
The Crown Range was closed to all vehicles but opened to vehicles with chains at 12pm. SH73 Springfield to Arthurs Pass was also closed to towing vehicles but has since full reopened.
SH94 Te Anau to Milford Rd is closed from Hollyford Rd Junction to Chasm, with heavy rain and snow increasing the avalanche hazard.
Trucker Steve Gray was stuck in Arthurs Pass. He said the snow was starting to mount around him.
"In front of me, the hills are looking fairly white and it's still coming down so it could be a while yet."