Tom Lee / Stuff
The Waipa River in Waikato overflowed its banks last week. Heavy rain is forecast for the west of the South Island for the next few days, with severe storms in the east of the island.
Heavy rains are forecast to fall from western South Island to northern Otira during Sunday, while severe storms are expected in most eastern parts of the island.
It was “probably a severe weather event,” MetService said, and follows a cold night for much of the country. The coldest nighttime temperature recorded by MetService was -11.6°C at Mt Cook Airport, while Christchurch dropped to about -5 °C, Upper Hutt to about -2 °C, Hamilton to about 1 °C, central Auckland to about 5° C, Waiouru to -3°C and Twizel to -8C.
Contrary to the wild weather forecast for the South Island, much calmer weather is expected in the North Island over the next few days, with the exception of Wellington and southern Wairarapa.
At least some rain is forecast for almost the entire country for Wednesday.
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An active front was predicted to approach the South Island from the southern Tasman Sea on Sunday and then move northeast across the island Monday to Tuesday, MetService said.
The front, preceded by a strong damp and unstable northwesterly current, was expected to bring significant heavy rainfall to the western and central parts of the South Island and severe storms to Fiordland and the eastern parts of the South Island, including Wellington and southern Wairarapa .
MetService had heavy rain warnings, starting at various times on Sunday, for Westland south of Otira, the headwaters of Canterbury south of Arthur’s Pass, the headwaters of Otago and Fiordland.
There is also a heavy rain watch for Buller south of Mokihinui from 9am Monday.
In the Westland and around the Main Divide in Canterbury, up to 450mm could fall in about two days, MetService said. About 180mm could fall near the Westland coast, and up to 300mm could fall within 20-30km east of the Canterbury gorge.
Civil Defense Emergency Management Canterbury said MetService had been told the spillover of rain into the region could be “unusually significant”.
A wind warning for Canterbury said there could be some north-westerly storms in exposed areas from 6pm on Sunday, with gusts up to 150km/h in the High Country and 120km/h further east.
Wind gusts can reach 80mph in Otago from 1pm on Sunday, and 120km/hr from 11am Sunday in Fiordland, Southland and Stewart Island, and 120mph in Marlborough from 2am Monday.
Winds can approach heavy gale force in exposed areas from 8 a.m. Monday in Wellington and Wairarapa south of Greytown from 8 a.m.
A mostly beautiful Sunday is expected for Auckland, then a mostly cloudy Monday with northern and isolated evening showers, followed by occasional showers and northeast on Tuesday.
A dry Sunday was expected for Wellington, with the north strengthening in the afternoon. Some showers and north-westerly storms are forecast for Monday, and some showers on Tuesday, along with strong northerly winds, which will ease later in the day.
After a cold night, Christchurch got off to a good and frosty start on Sunday, but MetService expected north to northwest winds to strengthen in the afternoon, with gusts of up to 75 mph on unprotected parts of the Banks Peninsula by evening.
The north was expected to be strong, with a chance of showers, in Christchurch on Monday, with rain to arrive in the afternoon on Tuesday, with northerly winds changing to the southwest.