Heavy downpours and thunderstorms are possible today in already saturated areas of the North Island.
Wild weather caused several streets and houses to flood in Auckland and Northland yesterday afternoon following periods of heavy rain.
The Fire Service went to about 20 weather-related call-outs, most due to blocked drains.
More than 200 lightning strikes were also recorded from Northland to Taranaki between 3.30pm and 4.30pm yesterday.
The same areas could be hit with further downpours and thunderstorms today, MetService says.
"There's a messy low sitting over the North Island so there could be showers again which explode in the afternoon," a spokeswoman said.
Eastern parts of the North Island can also expect the rainy weather to continue today, after a weekend full of flooding, slips, and dangerous roads.
Up to 120mm of rain was expected around parts of Gisborne overnight, and a severe weather warning remains in place until 9pm.
Up to 90mm of rain was expected in parts of the Coromandel Peninsula overnight, but the severe weather warning is due to end this morning.
"Both these regions have had significant rainfall accumulations during the last few days, and this rain could exacerbate any issues, such as surface flooding and slips," the MetService said.
"Streams and rivers are likely to remain high and could rise further for a time."
MetService meteorologist Lisa Murray said heavy rain would remain today for the Bay of Plenty, Gisborne and Hawke's Bay, and parts of northern Taupo.
Meanwhile, a storm set to batter parts of Australia but will have lost its teeth by the time it reaches New Zealand.
South Australia is to be hit by a severe storm today, which includes heavy rain and lightning.
"The low itself heads to the south of us. Extending from that low there is quite an active trough which will have a front in it.
"That is going to affect New Zealand over the weekend. It's going to bring rain, especially to western areas of the country."
All areas in western parts of the country are going to get wet. Eastern areas might also get the odd shower.
Main centres outlook
Dunedin: Mostly cloudy with possible showers. Northeasterlies. High 15C
Auckland: Showers, some possibly heavy and thundery in the afternoon. Light winds. High 18C.
Hamilton: Showers, some possibly heavy and thundery in the afternoon. Easterly breezes. High 17C
Tauranga: Rain with heavy falls. Easterly winds. High 16C
Wellington: Fine spells developing in the afternoon. Light winds. High 16C
Christchurch: Cloudy. Drizzle clearing by the afternoon. Northeast winds. High 14C
