"Bloody hell, Auckland ... that was bloody close as we heard a snap and pop. Never heard thunder [like] that before," one person wrote on Twitter.
"Holy, bro. I still didn't sleep and was watching Squid Game ... and literally jumped out of bed from the thunder. Auckland for you," another said.
Thousands of lightning strikes
Up to 4000 lightning strikes have been recorded around New Zealand and coastal waters over the past 12 hours.
The National Institute of Water and Atmospheric Research posted the feat online just before 8am.
Several weather stations reported rainfall accumulations of up to 20mm; including in the Auckland city centre, Mt Albert and Birkdale. Other stations saw rainfall accumulations of up to 15mm.
Surface flooding is being reported on several Auckland roads and Fire and Emergency has responded to a weather-related call-out.
The weather event has since moved away from Auckland and is now causing heavy rain in and around the Bay of Plenty.
Severe weather warnings
An orange heavy rain warning remains in place in the eastern Bay of Plenty and the Gisborne Ranges, Westland and the headwaters of the Canterbury Lakes.
The warning in the Bay of Plenty east of Ōpōtiki and the ranges of Gisborne is in effect until at least midday and locals are told to expect between 80mm to 110mm of rain to accumulate in those areas.
Peak rates of 15mm to 25mm/h are on the forecast.
Heavy rain is forecast in Christchurch, Timaru and Dunedin today, and northwesterlies could be strong at times in Wellington.
A heavy rain warning is in place in Westland south of Otirā until 9am.
"Periods of heavy rain, with thunderstorms possible," MetService says.
A further 60mm to 80mm of rain is expected about the ranges on top of what has already fallen, with lesser amounts near the coast.
"These amounts will bring the totals for the event to around 200mm to 250mm about the ranges. Peak rates of 15mm to 25mm/h about the ranges," locals are told.
People in those areas are warned that streams and rivers may rise rapidly as a result and surface flooding and slips are possible. Driving conditions may also become hazardous.
