Mhlongo said scattered showers would affect Northland at the start of the day before a front moves through in the second half of the day.
“They also have a chance of periods of heavy rainfall coming through in the afternoon,” he said.
The forecaster said strong winds would affect the North Island.
MetService has issued a strong wind watch for Northland from 2pm until 10pm.
Mhlongo said wind gusts were forecast to reach about 100km/h in exposed places.
He said the Auckland region would face similar conditions throughout the day.
“Scattered showers with periods of rain coming through in the afternoon. There is also a risk of squally thunderstorms coming through in the afternoon.”
What’s in store for King’s Birthday weekend?
MetService meteorologist Mathapelo Makabulane told the Herald Kiwis should expect a “noticeable cooler feeling” in the air as winter begins this weekend.
She said that would be due to a southwesterly flow over the country.
Makabulane said overall, the long weekend was not looking like a washout at this stage, but there would be periods of showers.
She said coastal areas in the western parts of the country, as well as the lower South Island, could have breezy southwesterlies which might create some large waves.
“That’s maybe a bit of an early heads-up for anybody who is thinking about being near the coast in those areas.”
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