The North Island is in the firing line for more wild weather with hail, severe thunderstorms and gale-force winds expected on Tuesday.
MetService said a slow-moving low and associated fronts are affecting northern parts of the country, which has seen them issue weather warnings and watches for the North Island.
NIWA warns rain totals by Tuesday evening for the east of the upper North Island could be "impressive" and bring nearly a month's worth of rain in two days.
"Some may see nearly a month's worth of rain in two days. This amount of rain in a short period of time increases the odds of flooding/slips," NIWA said.
It also warned river flows are forecast to become well above average to extremely high on Tuesday, which increases the chance of river flooding.
The wild weather has also seen the Coromandel Peninsula record 500 lightning strikes between midnight and 5am on Tuesday.
Weather warnings and watches
The wild weather has seen MetService issue eight weather warnings and watches for the North Island for Tuesday. The Coromandel Peninsula and the Bay of Plenty are expected to see the worst of the conditions, with a severe thunderstorm watch in place until 8am on Tuesday.
MetService said a rain band is expected to affect the Coromandel Peninsula and the western Bay of Plenty on Tuesday morning, bringing heavy rain.
The forecaster warns there is also a moderate risk of thunderstorms producing heavy rain with intensities of 10 to 25mm/h and small hail.
"Additionally, some of the thunderstorms could become severe bringing localised downpours of 25 to 40mm/h," MetService said.
"Rainfall of this intensity can cause surface and/or flash flooding, especially in low-lying areas such as streams, rivers or narrow valleys and may also lead to slips. Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain."
A heavy rain warning is in place for the Coromandel Peninsula until at least 12pm on Tuesday and Gisborne about and north of Tokomaru Bay until 6pm on Tuesday.
MetService said both these areas can expect 120mm of rain and peak rates of 25mm/h, with thunderstorms possible.
Hawke's Bay north of Napier and Gisborne south of Tokomaru Bay is also in the firing line, with heavy rain expected, which has seen MetService issue a watch.
A strong wind watch has also been issued for the Bay of Plenty east of Whakatane, Taupō, Tongariro National Park, Taumarunui, Waitomo and south Waikato and Taranaki until Tuesday afternoon.
