A key transport route at the top of the South Island has closed due widespread flooding.
State Highway 1 south of Picton, a key route for traffic and freight from the Interislander ferry, closed earlier this evening between Koromiko and Spring Creek.
There are no local detours.
Heavy rain has been pummelling the Tasman and Marlborough regions, causing widespread travel disruption, flooding and evacuations.
Earlier, a man was taken to hospital in a serious condition after climbing a tree to escape rising floodwaters near Blenheim.
Emergency services say the man was trapped in his car on Kaituna-Tuamarina Road along the Wairua River near Kaituna around midday.
Firefighters say he managed to get out and climb a tree, before being rescued by a specialist water response team about an hour later. St John said they took the man to Wairau Hospital.
"[It’s] certainly more widespread than what we’ve had over the last few years, where they’ve been really, really isolated to specific parts," King said.
A number of other roads around the top of the South Island remain closed including State Highway 63 from Renwick to Saint Arnaud.
However, State Highway 6 between Nelson and Blenheim has reopened, along with State Highway 60 between Richmond and Collingwood.
Meanwhile, Auckland has been hit by severe thunderstorms and torrential rain.
Dozens of domestic flights bound for or departing from Auckland Airport have been cancelled or delayed due to the severe weather conditions.
Auckland Airport said 21 flights had been cancelled and 11 flights delayed.
Strong winds lifted a roof and left a commercial building partially collapsed in the suburb of Blockhouse Bay.
Further south, a state of emergency has been declared for the Nelson Tasman region as a result of severe weather and evacuations.
Tasman District Council said the declaration would allow agencies to rapidly respond, with slips and flooding across the region and further rain forecast.
Nelson Tasman Civil Defence information manager Paul Shattock this afternoon said a significant number of people had chosen to evacuate as heavy rain continued to lash the region.Some have been evacuated in Brightwater and Upper Moutere and people in Riwaka may need to leave.
"We're starting to see some self-evacuations in the Motueka Brooklyn area, there were some round Brightwater and Tapawera as well," Shattock said.
Shattock said smaller rivers were a major area of concern.
"Our larger rivers seem to be coping quite well, it's some of the smaller rivers because the ground is so saturated if we have any localised downpours then those smaller streams and rivers could rise very rapidly and lead to further floods," he said.
"The Wai-iti is probably one of the rivers they're looking at most closely at the moment, it seems to be running very high."
Fire and Emergency New Zealand (Fenz) has activated its Local Coordination Centre in Nelson to coordinate its response activities across the whole top of the South area.
A local state of emergency is also in place for part of Marlborough, where 60 households in Spring Creek near Blenheim were ordered to evacuate because of fears a Wairau River stopbank might not hold.
Fenz has responded to 31 weather-related callouts in the Nelson-Marlborough district since 4am.
Fenz said there was one significant rescue where its specialist water rescue team rescued a person trapped in a car in floodwaters in Lower Moutere about 5.05am.
MetService has issued several severe weather warnings and watches across the country.
Parts of Northland and Auckland are under a severe thunderstorm warning. The thunderstorms are expected to be accompanied by torrential rain.
Meanwhile, a heavy snow watch has been issued for Central Otago, Southland north of Lumsden, also inland Dunedin and Clutha until noon Saturday.
