MetService says it's going to be a "thundery Thursday" as heavy rain, localised downpours and thunderstorms are forecast for swathes of the North Island and the top of the South Island.
A large low-pressure system moved across parts of the lower north and upper south overnight, which has now been upgraded to include more areas across the entire North Island.
Alongside watches and warnings already in place, the forecaster this morning issued a severe thunderstorm watch for Northland, Great Barrier Island, Coromandel Peninsula, Gisborne, Hawke's Bay, Taihape, Wanganui, Manawatū, Tararua, Wairarapa from today into Friday.
It said a "moist unstable northwesterly flow is expected to bring frequent showers and possible thunderstorms" for these regions, with a moderate risk of severe thunderstorms with downpours bringing localised rainfall rates of 25 to 40 mm/h.
Orange heavy rain warnings and watches were still in effect for many parts of the country, including the top of the South Island where downpours could reach a maximum of 120mm/h.
"Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible.
"Clear your drains and gutters to prepare for heavy rain. Avoid low-lying areas and drive cautiously."
MetService meteorologist Katie Lyons told 1News there were lightning strikes confined to the west overnight, and most of them were over water rather than land.
"What we do expect as the day goes forward is that sort of stuff to move over the country, so we have a few risk areas for thunderstorms, mainly the northern half of North Island for this morning.
"Then that flows through to the southern half of the North Island for this afternoon and evening and through tonight, as well as for this morning and this afternoon, the very top bit of Nelson and Marlborough for this morning and this afternoon.”
Lyons said while lightning strikes may be exciting, the forecaster was "really focused" on the "double-whammy" element of localised heavy rain falls and high hourly rates.
"It’s those elements where we could get those really high hourly rates and then on top of that, broad scale, heavy rain for a prolonged period of time," she said.
MetService said the rain would ease from the west on Friday morning.
Full list of watches and warnings
Severe Thunderstorm Watch
Northland - 13 hours from 11am to midnight tonight.
Great Barrier Island, Coromandel Peninsula - 17 hours from 1pm today
Gisborne, Hawkes Bay, Taihape, Wanganui, Manawatū, Tararua, Wairarapa - nine hours from 1pm
Heavy Rain Warning - Orange
Bay of Plenty and Rotorua - 25 hours from 9am today
Marlborough about and north of Ward - 19 hours from 8pm Wednesday
Heavy Rain Watch
Auckland and Waikato - 12 hours from 1pm today
Taranaki, Waitomo, Taumarunui, Taupo and Tongariro National Park - 23 hours from 2am today
Nelson and Tasman Districts north of Nelson Lakes - 14 hours from 8pm Wednesday.
Wellington - 15 hours from 6am today
Marlborough south of Ward, and the Kaikoura Coast - 21 hours from 9pm Wednesday
The morning's headlines in 90 seconds, including rough weather on the way, and a massive cocaine seizure. (Source: 1News)
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