Aucklanders have been warned to brace for a wild afternoon of weather with severe thunderstorms, heavy rain and even hail expected to lash the city.
The wild weather comes as a slow-moving low-pressure system lies east of Northland and is gradually weakening, according to MetService.
This has seen MetService issue a severe thunderstorm watch for Auckland, Coromandel Peninsula, Waikato and the Bay of Plenty from 2pm until 8pm on Monday.
The forecasting agency warns thunderstorms are expected to develop in the northern regions of the North Island on Monday afternoon and continue into the evening, producing heavy rain and hail.
"However, in areas of Auckland, Waikato, Coromandel Peninsula, and Bay of Plenty west of Rotorua, there is a moderate risk that some of the thunderstorms could become severe," MetService said and warned these areas could see localised downpours of 25 to 45mm/h.
MetService forecaster Mmathapelo Makgabutlane told Newshub the areas under the severe thunderstorm watch should expect "quite intense downpours" of rain.
"That amount of rain spread over a few hours probably wouldn't pose too many problems, but squeezed into an hour, a short time period could bring some possible impacts such as surface flooding or flash flooding and very rapidly rising streams and rivers if it does happen to form over those kinds of places. So those intense downpours of rain is what we're keeping a very close eye on," she said.
She urges people to keep an eye on the forecast as the severe thunderstorm watch could be upgraded to a red warning.
"Even though the conditions and the atmosphere are ripe for those severe thunderstorms, not everyone will get one. So even if you are in that area, don't be surprised if you don't necessarily get one today," Makgabutlane told Newshub.
An orange heavy rain warning is still in effect for Gisborne from Tolaga Bay northwards until 11am on Tuesday with a further 120mm of rain at peak rates of 10-15mm/h expected.
The Ruahine Range and the inland ranges of Hawke's Bay also have an orange warning in place until 2am Tuesday but MetService said the heavy rain has currently eased but is expected to become heavy again around midday.
"A further 70 to 90mm of rain is expected to accumulate. Peak rates of 15 mm/h, especially this afternoon and early evening," MetService said.
For the areas under an orange heavy rain warning, MetService warned, "Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous".
Heavy rain watches are also still in place for Gisborne south of Tolaga Bay until lunchtime on Tuesday and the Wairarapa from about Carterton northwards, the Tararua District not including the Ruahine Range and Hawke's Bay not including the inland ranges until 1am Tuesday.
Severe Thunderstorm Watch
Area: Auckland, Coromandel Peninsula, Waikato, Bay of Plenty
Period: 6hrs from 2pm - 8pm Mon, 20 Nov
Forecast: Thunderstorms are expected to develop about northern regions of the North Island this afternoon and continue into the evening, producing heavy rain and hail.
Heavy Rain Warning – Orange
Area: Tairawhiti/Gisborne from Tolaga Bay northwards
Period: 26hrs from 9am Mon, 20 Nov - 11am Tue, 21 Nov
Forecast: Expect a further 100 to 120 mm of rain. Peak rates of 10 to 15 mm/h. Note, showers are expected to continue in the area after the heavy rain has eased.
Area: The Ruahine Range and the inland ranges of Hawke's Bay
Period: 17hrs from 9am Mon, 20 Nov - 2am Tue, 21 Nov
Forecast: Heavy rain has currently eased, however it is expected to become heavy again around midday and a further 70 to 90 mm of rain is expected to accumulate. Peak rates of 15 mm/h, especially this afternoon and early evening.
Heavy Rain Watch
Area: Tairawhiti/Gisborne south of Tolaga Bay
Period: 27hrs from 9am Mon, 20 Nov - noon Tue, 21 Nov
Forecast: Periods of heavy rain. Rainfall amounts may approach warning criteria.
Area: Wairarapa from about Carterton northwards, the Tararua District not including the Ruahine Range and Hawke's Bay not including the inland ranges
Period: 16hrs from 9am Mon, 20 Nov - 1am Tue, 21 Nov
Forecast: Periods of heavy rain, especially about higher ground. Rainfall amounts may approach warning criteria.