Thunderstorms and lightning strikes are carving a path down Northland - and north Auckland could be next in the firing line.
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"Heavy downpours in Northland are growing and one area is tracking into northern Auckland with thunderstorms right now," WeatherWatch warns on Twitter.
"Some downpours may be heavy enough to cause surface flooding."
MetService says the line of thunderstorms is expected to affect the city in the next one-two hours.
"Keep an eye on the latest rain radar and be prepared for potential small hail, lightning and surface flooding in brief heavy rain," it warns.
Lightning trackers show over 500 strikes in the past hour, with one intense thunderstorm near Whangarei Heads, Northland causing 300 strikes alone, NIWA says.
"Active thunderstorms over parts of Northland. Note the number of lightning strikes in the past one hour!" it tweeted. "When thunder roars, head indoors."
MetService says the thunderstorms are due to a low over the Tasman Sea.
"Although some good fine breaks will be seen over the upper North Island this morning, these glimpses of the sun will be interjected with heavy and possibly thundery showers," meteorologist April Clark said on Monday morning.
"Showers will turn to persistent rain for the western Bay of Plenty, who are under a heavy rain watch, and the Coromandel, who have an orange warning due to a slow-moving front over the area."
Newshub.