Showers and rain - at times heavy - is forecast to continue today before a return to hot conditions to end the week.
MetService meteorologist Karl Loots said a rain band was hovering over the central North Island today.
Much of the North Island would see showers as a result, with the heaviest falls forecast in the afternoon.
After its first day of rain in 18 days yesterday, today Auckland would start with a few showers with fine breaks, before showers returned, possibly heavy, in the afternoon and evening. A high of 23C was forecast.
Unstable conditions were expected over northern and central parts of the North Island in the afternoon and evening, with a moderate risk of thunderstorms from Waikato, Coromandel Peninsula, Bay of Plenty and Gisborne down to Waitomo, Taumarunui, Taihape and Hawke's Bay, mainly inland.
A refreshing cooler air mass is making its way up the country đŹïž
— NIWA Weather (@NiwaWeather) January 13, 2019
Don't get used to it! Hot weather returns later this week thanks to our friends across the Tasman đ„” pic.twitter.com/3FOAESDYpe
These thunderstorms could bring localised heavy rain of up to 25mm per hour and hail up to 20mm in diameter.
A heavy rain watch was in place for Hawke's Bay from 9pm tonight to 11pm Wednesday, with periods of heavy rain, especially about the hills and ranges, forecast.
A ridge of high pressure had spread over the South Island bringing mostly fine weather for Tuesday, with just some morning and evening cloud.
On Wednesday the ridge covering the South Island would continue, while a low just to the northeast of the North Island would move slowly eastwards.
Many areas of the North Island are seeing the brunt of this weather system. Higher stations are seeing some high rainfall numbers with Tongariro and Mt. Ruapehu have reported between 20-30mm of rain in the last 12 hours. https://t.co/Yjbq0jxdqz. ^MB pic.twitter.com/JHQesMkTBb
— MetService (@MetService) January 14, 2019
This low was expected to bring significant rain to Gisborne and Hawke's Bay.
The low should move away to the east on Thursday while a weak trough moved on to the south of the South Island.
A front was forecast to approach the South Island from the Tasman Sea late on Friday, then move over the south of the South Island on Saturday, bringing a period of heavy rain to the west coast and strong northwesterly winds to the south of the South Island.
A few showers, chance heavy in the morning. Southwesterly. 24C high, 16C overnight.
Early showers, then fine breaks. However, a few afternoon and evening showers, possibly heavy. Light southwesterly. 23C high, 16C overnight.
Fine spells. A few afternoon and evening showers, chance heavy and thundery. Light winds. 23C high, 14C overnight.
A few showers, chance heavy and thundery. Light winds. 23C high, 17C overnight.
New Plymouth Fine spells and a few showers. Southerlies, strong at times. 22C high, 15C overnight.
Napier Showers, chance heavy. Southerlies developing. 23C high, 18C overnight.
Whanganui Fine spells, but chance shower. Fresh southerlies. 22C high, 15C overnight.
Wellington Overcast, with showers easing afternoon, clearing evening. Strong cool southerly. 17C high, 13C overnight.
Nelson Fine. Light winds and afternoon sea breezes. 23C high, 12C overnight.
Christchurch Morning cloud and possible drizzle, then fine spells. Cloud increases again evening. Southwest breezes dying out. 18C high, 8C overnight.
Dunedin Fine, apart from morning and evening cloud. Light winds. 19C high, 12C overnight.