Lightning sparked across the lower North Island skies on Saturday night, and may be responsible for setting a house on fire.
Footage sent to Newshub shows lightning arcing across the heavens over Totara Park in Upper Hutt.
Fire and Emergency attended a blaze on Sinclair St in Upper Hutt. Fire investigators will be at the scene Sunday morning, but it's believed it may have been struck by lightning..
One person was treated for smoke inhalation.
It follows a Friday that saw nearly 100,000 lightning strikes in just 24 hours.
There is also surface flooding in Wellington, with NZTA cameras showing a roundabout on State Highway 1 in Plimmerton largely underwater.
MetService has issued severe thunderstorm watches for much of the North Island and West Coast of the South Island.
On Sunday morning, it says there is "a general low risk of thunderstorms from Northland [to] the central high country and the Bay of Plenty, but the risk rises to moderate towards noon in the south of Northland, Auckland, Coromandel Peninsula, Waikato, Waitomo, Taumarunui, Taupo, Bay of Plenty and Rotorua," the forecaster said.
"These storms may be accompanied by heavy rain, 10 to 15mm per hour and strong wind gusts, 90km/h."
Tornadoes are also a possibility in Taranaki, MetService said.
NZTA said road closures on Sunday morning include State Highway 2 northbound, north of the Kelson/Major Drive intersection, SH58, and SH 1 through Mana.
"We're advising people to avoid travel along these routes unless absolutely essential until at least lunchtime today, but which time the water will likely have receded," said spokesperson Mark Owen.
SH58 is so damaged it may remain closed all day.
The afternoon will likely see downpours intensify.
"The combination of afternoon heating and a very humid air mass is expected to create conditions favourable to afternoon and evening thunderstorms across large parts of inland North Island.
"There is a high risk of thunderstorms from Northland to Taranaki, the central North Island high country, Coromandel Peninsula and the Bay of Plenty. Horowhenua and Kapiti Coast are also affected."