Flash flooding has struck in the Waikato, as a menacing storm unleashed a torrent of rain on Te Awamutu.
There is surface flooding in several parts of the town, which is 30km south of Hamiltonm and a tornado reportedly travelled down the main street of the town.
Thunderstorms and heavy rain have caused flooding and closed roads in the North Island, and more rain is expected later this afternoon.
An Air New Zealand flight from Wellington to Hamilton had to be diverted after a suspected lightning strike.
"The aircraft is being assessed by engineers in Auckland and customers were put onto another aircraft to operate Auckland to Hamilton," the airline said.
"Lightning strikes are not uncommon – aircraft are designed with this in mind and our pilots train for this scenario."
About 3.45pm, MetService issued a fresh severe thunderstorm warning for South Waikato, Whakatāne, Taupō and Rotorua.
"These thunderstorms are expected to be accompanied by torrential rain and frequent lightning.
"Torrential rain can cause surface and/or flash flooding about streams, gullies and urban areas, and make driving conditions extremely hazardous.
"Frequent lightning is dangerous to people and livestock, especially those exposed outdoors or on the water, and can cause power surges and damage to electrical equipment."
In Taranaki, more rain has fallen in the last 18 hours than all of last November.
State Highway 3 has been closed by a slip near Hawera, and some streets in New Plymouth have been closed by flooding.
The New Plymouth District Council said the severe weather had caused surface flooding and sewerage overflows in parts of the district.
"Residents are urged to slow down, take care and drive to the conditions and to not swim or collect kai from some waterways," the council said in a statement.
Metservice said Taranaki had 90mm of rain before midday - more than the 79.2mm that fell in the entire month of November last year.
In the space of 75 minutes, Fire and Emergency New Zealand responded to around 30 calls regarding flooding in the Te Awamutu and Taupō area, Fire and Emergency shift manager Paul Radden said.
"We had crews from Hamilton, Te Rapa, Cambridge and Te Awamutu all down in Te Awamutu assisting and Taupō had their three crews out."
The crews attended both commercial and residential locations.
"[The fire crews could be doing anything] from clearing blocked drainage on the roadway to help the water subside [to] pumping water out of properties to help the owners."
More heavy rain was forecast for today and overnight in the region. Metservice's heavy rain watch was in place until 6pm and its thunderstorm watch was in place until 8pm.
However Metservice meteorologist Lewis Ferris says the majority of the heavy rain fell last night.
"At the moment there are still a few showers that are lingering around Taranaki, and we will get a few more come in this evening and even into Thursday. The good news is the most heavy and persistent rain has eased for Taranaki."
Further north, the heavy showers that belted parts of Auckland have moved off to the east.
However, bands of heavy rain have been popping up quickly over some parts of the city this afternoon.
"Just in the last hour we've seen some very heavy showers pop up very quickly over the likes of Auckland Airport and Devonport. These showers now are quite isolated, they're quite small, so although parts of Auckland will see them, we don't expect them to be so widespread the entire city will be affected at the same time."
However a severe thunderstorm watch which encompasses Auckland, remains in force until 8pm, he said.
"I'm not saying [the rain] is completely done [in Auckland]. The atmospheric conditions, they are still present, so there is still the ability to form these very heavy localised showers, it's just whether they actually do, and where they actually form."
In Rotorua, the Lakes Council said there had been surface flooding on a number of streets and warned motorists to take care this evening.
The chaotic weather was being caused by a low approaching from the Tasman Sea, and was causing heavy rainfall and thunderstorms across the North Island and the top of the South Island.
There is a heavy rain warning in place for the Bay of Plenty, Taranaki (north of Eltham), and the Kaikōura Coast and ranges until this evening.
There is also a severe thunderstorm watch in place for Auckland, Coromandel Peninsula, Waikato, Waitomo, Taumarunui, Bay of Plenty, Rotorua, Taupō, Hawke's Bay, Taranaki, and Taihape until 8pm tonight.
That could mean rainfall of between 25 and 40mm an hour. Metservice said rainfall of this intensity could cause surface or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and could also lead to slips.
Showers are forecast tomorrow throughout the North Island, with possible thunderstorms in Taupō, Manawatu and the Tararua District.
The roads with surface flooding in Rotorua include:
• Sunset Road
• Hathor Street
• Exeter Place
• Ruby Place
• Emerald Place
• Barnard Road
• Hamurana and Dalbeth intersection (both lanes)
• Hamurana and Oturoa intersection (both lanes)
• State Highway 36 and Waiteti intersection (both lanes)
• Warwick Drive (both lanes)
• Te Ngae Road - between Puketawhero Park and Hannahs Bay