Most of the country has woken up to a wet, soggy morning for the third day in a row, but the heavy rain is easing in most of the North Island and instead moving south to Canterbury.
Multiple crashes on Auckland's motorway are also causing delays for those heading both north and south.
A crash near Princes St blocking two northbound lanes has been cleared but there are still delays for motorists between Manukau and Mt Wellington.
Those travelling from the North Shore should also brace themselves for a slow trip into the city after a crash on the Onewa Rd southbound on-ramp.
A Severe Thunderstorm Watch has been issued for southern parts of the North Island this afternoon and evening. Localised downpours are possible. ^PL https://t.co/GleiErDxGJ
— MetService (@MetService) December 14, 2021
The weather paired with an ongoing issue with Wellington Airport's Airway's Instrument Landing System has seen four regional flights cancelled so far this morning. An airport spokesperson said the total number of flights disrupted today will depend on how quickly weather conditions improve and when the Airway's issue is resolved.
However Wellington's weather isn't expect to improve with a severe risk of thunderstorms this afternoon likely to bring downpours of rain between 25 and 40mm to the capital and Wairarapa until 8pm, the Wellington Region Emergency Management Office has warned.
Meanwhile, the heavy rain and wind warnings and watches have this morning lifted for most of the North Island, but the rain is still pouring down in the Bay of Plenty and Gisborne.
There is a heavy rain warning in place for Bay of Plenty until 3pm today with a 70 to 100mm of rain expected to fall and between 150mm and 180mm in inland areas east of Whakatāne, according to MetService.
The heavy rain warning for Gisborne is in place until 4pm with 120 to 160mm of rain about and north of Ruatoria, and 70 to 100mm from south of Ruatoria to Tokomaru Bay.
Heavy rain has eased over northern parts of the country but has moved southwards onto Canterbury https://t.co/prKU7O2R01 ^PL pic.twitter.com/65kMaqbRHe
— MetService (@MetService) December 14, 2021
MetService is warning the heavy downpours in both areas could cause streams and rivers to rise rapidly. Motorists are urged to take care as surface flooding and slips are possible.
The rain doesn't stop falling for the South Island until later this afternoon with heavy rain warnings also in place for Tasman, Eastern Marlborough south of Blenheim and Buller, and Westland north of Hokitika.
Police are asking motorists to avoid or delay travel between Blenheim and Kaikōura this morning due to multiple slips on State Highway 1. They are also concerned about the risk of injury due to rockfall.
SH1 NORTHERN MWY - 7:30AM
— Waka Kotahi NZTA Auckland & Northland (@WakaKotahiAkNth) December 14, 2021
A crash on the Onewa Rd southbound on-ramp will cause delays for citybound motorists heading for the Harbour Bridge from Onewa Rd this morning. Allow extra time. ^TP pic.twitter.com/D95KV6jJuO
Strong southeast winds will also batter Buller and Westland north of Hokitika with warnings of severe gales in exposed places until 3pm today.
The Christchurch City Council is warning Lyttelton residents could see stormwater flows on some streets while work is undertaken to urgently repair a collapsed storm water drain.
"With heavy rain expected throughout Wednesday night, there will be heavy stormwater flows running down those streets.
"Temporary traffic measures will be in place to prevent people from accessing the area and sandbags are being deployed around certain properties as additional protection," a spokesperson said.
MetService meteorologist Angus Hines told RNZ surface flooding was likely.
"Just over a 24-hour period between 100mm and 150mm of rain is expected to pile up to parts of Canterbury and Marlborough," he said.
"That is a lot for that part of the country. Take Christchurch for example, their average December rainfall is about 47 millimetres on average across the entire map so there's a chance that Christchurch could well and truly exceed that in a day."
Earlier in the week, heavy rain caused extreme flooding in Manawatu and the Fire Service responded to more than 30 call-outs to properties flooding in Feilding, Bunnythorpe and the Palmerston North area on Monday.
UPDATE 7:20AM
— Waka Kotahi NZTA Auckland & Northland (@WakaKotahiAkNth) December 14, 2021
Tow services have now fully cleared this crash with all 3 lanes north available again. Allow extra time this morning with significant delays from Manukau to Mt Wellington. ^TP https://t.co/On2Z0Ex4d5
At least two vehicles were involved in accidents caused by the flooding and a welfare centre was also set up in Feilding for those forced to evacuate their homes.
Footage has emerged of the flooding damage caused to a farm in Hunterville showing paddocks underwater and trailers, fence gates and hay bales strewn all over the property.
Meanwhile, Tropical Cyclone Ruby is forecast to continue moving southeast on Thursday, but has been downgraded and is tracking to remain offshore tomorrow afternoon and evening causing no impact to the country.
A large plume above Whakaari/White Island prompted questions.