"A warning for heavy rain is in affect now increasing until tomorrow evening."
MetService had forecasted 90mm to 120mm to accumulate by tomorrow afternoon in Coromandel.
Ms Roux said the rain could reach peak intensity of 156mm accumulating per hour tonight.
A severe weather watch for strong easterly winds reaching gale force was in place for North Auckland, Ms Roux said.
Auckland would see rain clearing through the morning and easterly winds easing.
Winter's final storm brought flooding that closed State Highway 10 at flood-prone Kaeo today.
The Northland Civil Defence Emergency Management Group said Northlanders had coped well with surface flooding "in usual spots".
The New Zealand Transport Agency closed the road north of the Kaeo River Bridge and told motorists they needed to use State Highway 1 for any journeys further north than Kaeo.
The Northland Regional Council reported that in the 30 hours from midnight Friday to 6am today, 188mm had already fallen on Kaeo's eastern hills, just a few millimetres short of the 196mm the area would usually receive for the entire month of August.
Ms Roux said the heavy rain would be moving towards Gisborne late tomorrow and into Tuesday.
The rest of the country would be mainly fine next week, Ms Roux said.
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Main centres:
Whangarei: Showers and fine spells with northerly winds tomorrow through to Wednesday. Highs 17C, lows 10C.
Auckland: Showers tomorrow with increasing fine spells Tuesday and Wednesday. Easterly winds easing. Highs 17C and lows 10C.
Hamilton: Rain tomorrow clearing by afternoon. Fine spells for Tuesday and Wednesday with lights winds. Highs 17C and lows 7C.
Tauranga: Rain tomorrow clearing by afternoon, Fine spells for tuesday and Wednesday. Highs 17C by Wednesday and lows 9C.
Wellington: Long, fine spells with southeast breezes easing by Wednesday. Highs up to 14C and lows 8C.
Christchurch: Fine spells and cloudy periods through to Wednesday. Highs 14C and lows 3C.
Dunedin: Fine spells and cloudy periods through to Wednesday. Highs 12C and lows 4C.
