People on the western side of Northland and Auckland are being warned to prepare for possible severe thunderstorms and small tornadoes to strike this afternoon.
A trough of low pressure covers northern and central New Zealand on Sunday, and MetService told the public it's a good day to "keep an eye on the rain radar" with "small tornadoes possible".
"About western parts of Northland and Auckland, there is a low risk of thunderstorms during the afternoon and early evening," it said on its website.
"Whether these thunderstorms occur or not, there are likely to be heavy showers in this area.
"If thunderstorms do occur, there is a low risk they may produce localised downpours, and possibly a small and very localised tornado."
There's also a low risk of thunderstorms later on Sunday from Waikato southwards to Wairarapa, including parts of Gisborne and Hawke's Bay - as well as for northern parts of the South Island.
Auckland Emergency Management has urged people to "get your household ready for this evening's rain".
"Clean out gutters and drains to reduce the risk of them overflowing," it tweeted.
"We will continue to keep you informed as we get intel from MetService."
And the risk of thunderstorms and localised downpours over parts of New Zealand increases on Monday.
"A trough brings rain to the northeast of the North Island during Monday morning with an associated moderate risk of thunderstorms for Gisborne and the far east of Bay of Plenty," MetService warned.
"Another trough is likely to bring a few showers to Northland, Auckland and Coromandel Peninsula during the morning. One or two showers may be heavy with a low risk of thunderstorms."
Then, in the afternoon, the trough is forecast to continue moving westwards across the upper North Island, and increase the risk.
"From Northland southwards to Taihape and central Hawke's Bay the risk of thunderstorms is considered moderate," MetService said.
"In these areas there is also a low risk that thunderstorms could become severe, producing localised downpours (25 to 40 mm per hour).
"This risk may be upgraded to moderate for some areas closer to the time, in which case a severe thunderstorm watch will be issued."
