More than 1000 lightning strikes have been recorded in two hours, as parts of the country brace for a deluge of heavy rain and stormy weather this weekend.
And in the South Island, emergency services are warning people to be prepared for flooding in some areas; with some Civil Defence agencies being placed on standby.
MetService said up to 1233 lightning strikes were recorded around the country in a span of 120 minutes.
The weather authority shared an image of its rain and lightning radar showing the data of the past two hours up to 11.15am.
It comes as parts of the South Island, in particular, are forecast to get a deluge of heavy rain and stormy conditions.
Canterbury is set to get the full brunt of the weather system.
MetService has issued a rare red warning for heavy rain for Canterbury south of Amberly. That warning will be valid from 3pm until Monday.
Those in Christchurch are being told warned that the deluge is expected to reach dangerous levels and has the potential to cause heavy flooding and slips that may make some roads impassable.
Depending on any damage caused, some communities may also become isolated for some time.
Shaun McCracken - the flood controller for the area from Hinds to Kaikoura - told Radio New Zealand the bulk of the rain will be from this afternoon onwards.
Rivers of concern include the Ashley, Selwyn, Ashburton, Opihi and Orari rivers along with the tributaries that flow into those rivers.
McCracken said river flows will be highest on Sunday and Monday.
Niwa is forecasting a rapid increase in river flows across Canterbury.
National Emergency Management Agency Communications manager Anthony Frith said when the rough weather set in, it could be serious.
"This has the poetntial to be quite a serious flooding event for some regions, and people need to take it seriously. Listen to the advice and instructions of their local authorities and local Civil Defence groups, and listen to the radio and other media. It's really important that people stay away from floodwater, please drive only if absolutely necessary."
Those in Auckland are also warned of gloomy weather conditions over the next few hours.
"A combination of king tides and strong north-westerlies bring possible coastal inundation to Auckland this weekend," MetService said.
Tides could reach up to 4.0m causing inundation around low-lying coastal places.