Heavy rain is on the way for the Coromandel, with isolated thunderstorms and between 100 to 150mm of rain expected.
That will include peak rates of 20 to 40mm per hour from thunderstorms, the remnants of which will produce showers into tomorrow.
"Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous," MetService wrote in its warning.
However, the weather is set to move one way and that was south, meaning a wet weekend for many parts of the country.
A heavy rain watch is in place in northern and eastern areas of Northland from 4pm today to 3am tomorrow.
"There are associated thunderstorms with that watch and there is also a severe thunderstorm watch in place for the eastern area of Northland and the Coromandel Peninsula from 8pm Wednesday until 11am Thursday," Ferris said.
There was a moderate risk of thunderstorms associated with this front, some of which may bring severe localised downpours of 25 to 40mm per hour.
For Northland and the far north of Auckland there was a risk of severe thunderstorms late this evening but the storms should then clear.
Parched Auckland is expected to get a decent dousing, with hopes the much-needed rain will top up the city's dam levels - sitting at just 44.8 per cent, down 0.2 per cent on yesterday.
The dams normally sit around 78 per cent at this time of the year.
A strong weather watch is in place for the city, with easterlies expected to rise to gales in exposed places, possibly reaching severe gales at times.
Lashing rain and north-easterly winds will be strong enough to toss around backyard furniture and possibly even cut power, Ferris said.
The Hūnua Ranges had received 57.5mm of rain the past week, while 41.5mm had fallen in the Waitākere Ranges.
Gales should also be expected.
A MetService spokesman earlier said a low-pressure system over the Tasman Sea, and its associated fronts, were forecast to move southeastwards onto the North Island over the next few days - bringing with it bad weather.
"The weather system should bring rain to much of the North Island by the weekend, but especially northern and eastern regions."
The weather will move down to the Bay of Plenty and west of Te Puke, including the Kaimai Range, tomorrow morning.
A heavy rain watch is also in place for Gisborne, north of Tolaga Bay.
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