A raft of heavy rain and thunderstorms are set to sweep the country on Saturday, hitting the North Island from midday.
MetService has issued a severe thunderstorm watch for Northland and Auckland for Saturday afternoon and evening.
A heavy rain watch is in place for Kaitaia, Whangarei, Taupo and Queenstown.
For the rest of the North Island, there's widespread risk of thunderstorms and localised downpours from late morning until night.
There's a moderate risk of some thunderstorms becoming severe, with localised downpours of up to 44mm.
A moderate thunderstorm risk in place for Canterbury, central Otago and north Otago.
MetService says any thunderstorms are likely to bring localised heavy rain of 10-25mm, hail, and possibly small tornadoes.
Intense rainfall can also cause flash flooding, the forecaster warns, especially in low-lying areas near streams, rivers or narrow valleys, which may also lead to slips.
There's a low risk of thunderstorms becoming severe in south Canterbury and central Otago.
There's a low risk of thunderstorms for eastern areas of the South Island from the afternoon.
MetService says driving conditions will also be hazardous, with surface flooding and poor visibility in heavy rain.
Holidayers travelling home should take extra care as surface flooding and heavy rain create hazardous driving conditions.
Daytime heating and afternoon wind convergences were expected to produce showers and thunderstorms from the Coromandel Peninsula to Hawke's Bay and the Tararua District this afternoon and evening.
Wet weather is expected to continue on Sunday for both the North and South Island, easing in the evening.
After abnormally dry conditions in northern Waikato, Auckland, and Northland, NIWA Weather says the coming rainfall is "welcomed news".