Thunderstorms are predicted again this morning with Auckland, Waikato, the Coromandel Peninsula and Northland in the firing line.
The storms will set the agenda for several days of windy and wet weather across the country.
An unstable west to southwest flow was affecting the North Island and the storms may be accompanied by brief heavy rain and small hail, MetService said.
There was also a low risk of thunderstorms over the west coast from Waitomo to Whanganui and over coastal Wairarapa, southern Hawke's Bay and the far east of Bay of Plenty.
Auckland and Northland could see between 5mm and 15mm in an hour during the spells of heavy rain.
Tomorrow, a broad trough over the North Island was expected to move away east early on Wednesday, while another front moved on to the South Island.
MetService warned any trick or treaters wanting to head out on Halloween that conditions looked a "treat" over the North Island and upper South Island but nasty over the lower South Island.
The front moving over the South Island was expected to then move northeast over the North Island on Thursday followed by a cooler southwest flow.
"This front brings a period of rain or showers to much of the country, but rainfall accumulations are not expected to approach warning amounts at this stage."
Northwesterlies would return on Friday and strengthen over the South Island ahead of another more active front.
The front was preceded by northwest gales and rain, which spread over the South Island from late Friday into Saturday.
There was a moderate risk that rainfall accumulations could reach warning amounts about Fiordland, the Otago and Canterbury headwaters, Westland, Buller, western Nelson and the Tararua Range from late Friday to Saturday.
"There is a low risk that northwest gales may approach severe gale about Fiordland, Southland, inland parts of Otago, Canterbury and Marlborough, with a moderate risk about the Marlborough Sounds, Wellington, Wairarapa and Tararua District," MetService said.
Whangārei: Showers, possibly heavy and thundery, easing late. Gusty westerlies.
High 17C Low 11C
Auckland: Showers, possibly heavy and thundery, easing late. Gusty westerlies.
High 17C Low 11C
Tauranga: Sunny spells. Showers, mainly from afternoon, when some could be heavy. Brisk westerlies, changing southeast evening. High 18C Low 10C
Whanganui: Showers, possibly heavy, clearing afternoon to fine spells. Fresh southerlies. High 16C Low 8C
Napier: Cloud increasing with a few showers, turning to rain this afternoon as southwesterlies pick up. High 20C Low 9C
Wellington: Cloudy, with showers easing afternoon. Strong southerlies. High 14C Low 8C
Christchurch: Rain, easing to fine spells and a few showers this afternoon. Southerlies, strong at times. High 11C Low 3C
Dunedin: Cloudy with a few showers, gradually clearing from afternoon. Fresh southwesterlies. High 11C Low 4C