Photo: Screenshot / MetService
MetService has issued watches for heavy rain and severe gales in the lower North Island and South Island.
They come as fronts embedded in a strong northwesterly flow are expected on Wednesday and Thursday.
Heavy rain is likely for Fiordland and Westland, but it was unlikely that these areas will reach their warning criteria of 150 mm in 24 hours, MetService says.
There is a high risk of periods of thunderstorms about Westland, Fiordland and the Southern Alps through the whole morning on Thursday, with a few thunderstorms spreading well east of the main divide into western parts of the Canterbury High Country and Queenstown Lakes.
There is also a moderate risk of thunderstorms about the Grey District, Buller and western Tasman Sea spreading to Stewart Island, and a low risk of a few thunderstorms spreading across mainland Southland, southern and western Otago, and to the Canterbury foothills at times, and also into remaining parts of Tasman/Nelson, the Marlborough sounds, and Taranaki later in the morning.
An unstable northwesterly flow will continue during the second half of Thursday, with embedded fronts crossing the country at times.
In the North Island, there is a moderate risk of thunderstorms about northern and western Northland, western Auckland, western Waikato, Waitomo, Taumarunui and northern Taranaki for a time in the afternoon and evening, and a moderate risk about eastern Bay of Plenty in the evening.
In the South Island, there is high risk of further thunderstorms at times about western areas from the Paparoa range to Fiordland and Stewart Island, including about the Southern Alps, and a moderate risk of thunderstorms about remaining parts of Buller during the afternoon. A low risk of thunderstorms covers other northern and western area during the afternoon and evening, and also a low risk of a few thunderstorms about Clutha, eastern Otago and southern South Canterbury in the afternoon.
North to northwest winds may approach severe gale in exposed places in the Wairarapa, Wellington, the Marlborough Sounds, Canterbury High Country, Fiordland, Southland northwest of Riversdale, Queenstown Lakes District and Central Otago from 4pm on Wednesday.
MetService warned there could be damage to trees, powerlines, and unsecured structures. Driving may also be difficult, especially for high-sided vehicles and motorcycles.
No road snowfall or heavy swell warnings were in place.