Meanwhile, forecaster Oscar Shiviti said a front moved across the Tasman Sea overnight, bringing a rain-maker that is expected to soak the upper North Island.
“For the most part, it’s going to be a pretty bad up there.”
Shiviti said thunderstorms were possible this morning before they turned into isolated showers in the afternoon.
He also said there was a risk of localised flooding.
MetService has issued a heavy rain watch for Northland, Auckland, Aotea Great Barrier Island and the Coromandel Peninsula.
The watches extend for 11 hours of rain until 8pm, with thunderstorms and local downpours possible.
The forecaster warned there was a “high uncertainty” on where the heaviest rain would fall and there was a moderate chance the watch could be upgraded to a warning in some areas.
Heavy rain watches were issued for the Bay of Plenty and Rotorua with a 24-hour watch for the Wairoa District beginning at 1am tomorrow.
The upper North Island will be “muggy, warm and humid” today, with temperatures in the mid-20s for most places and Hawke’s Bay expected to reach up to 30C.
Shiviti said the rain is likely to linger into tomorrow morning before easing off around midday.
Further south, 100km/h winds are expected in exposed areas of Wellington, along with thunderstorms and hail this evening.
A strong wind watch has been issued for the Kaikōura coast, Marlborough Sounds, Wellington and coastal Wairarapa for 10 hours from 5pm.
MetService said hail of up to 2cm in diameter was possible because of a cold front moving up the country throughout the day.
There is also a moderate chance of thunderstorms in the Westland ranges, the Canterbury high country and North Canterbury this afternoon.
As the front spirals off the side of the country, Shiviti said there might be some respite for a few days before another front moves over the country in the middle of the week.
Wet days and high temperatures could be a running theme for summer, according to Niwa’s seasonal climate outlook.
From around New Year, northeast “La Nina-like” conditions will bring more muggy, rainy weather to places such as Auckland and Coromandel.
“We’re looking at increased odds for rain events, possibly heavy ones, for the northern and eastern parts of the North Island – but also increased odds for dryness for areas like the west and southwest of the South Island,” Niwa forecaster Chris Brandolino said.
He added the muggy outlook for the northeast in late summer didn’t mean a repeat of the extreme La Nina summer of 2022-23; its unprecedented deluges proved the climax of a three-year run of the climate pattern.
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