South Island weather: Heavy rain and wind could bring flooding, slips

Public Interest Journalism funded through NZ On Air

Parts of the South Island and the lower North Island are expected to experience bursts of heavy rain with strong winds this weekend.

MetService earlier issued heavy rain warnings for Westland, Fiordland, the headwaters of the Otago lakes and rivers, and Canterbury from midday today.

Between 150 to 180 mm/h of rainfall is expected to fall, starting in Fiordland this afternoon with wind gusts of 120km/h in exposed areas.

A MetService spokesperson said the rain is expected to be intense within a short 12-hour period that may cause streams and rivers to rise rapidly.

“Heavy rain may cause streams and rivers to rapidly rise, causing surface flooding and slips.”

However, the rain is expected to lessen as it moves northwards towards the North Island tomorrow.

“It will have lost quite a bit of intensity and we’re not expecting any warning amounts of rain for the North Island.”

A watch is in place for Buller, starting overnight with the risk of damaging winds reaching 130km/h across Canterbury.

❗ Severe Weather Update

🌧 An active front moving northwards, starting in Fiordland this afternoon, is forecast to bring rainfall well above the minimum amount needed to justify an Orange Warning to the southern half of the West Coast and main divide of the Southern Alps. A… pic.twitter.com/DtgSXLvqaj

— MetService (@MetService) December 8, 2023

Forecaster Niwa said it will be a dry day for most of the country but Fiordland, Stewart Island and the lower West Coast were set to experience heavy rainfall.

“As we go into the afternoon and evening, an area of heavy rain moves up into the West Coast. Rainfall amounts will be pretty substantial.

“Rivers will rise rapidly during the course of Saturday afternoon and evening thanks to that heavy rainfall. We could be looking at some localised flooding in that part of the country,” Niwa said.

Niwa said strong wind gusts are expected to pick up from 2pm in the lower and central South Island.

“Particularly (in) high terrain, (with) strong to potentially even damaging wind gusts (you) might even see a little bit of tree damage, maybe some power outages as well.”

MetService urged residents in warning-indicated areas to prepare for the severe weather this afternoon.

“Before the winds pick up you can tie down those objects like trampolines, secure anything that might blow away like wheelie bins.”

Make sure to read the full details at https://t.co/qHyE5zzql5 if there's a Warning out for your area and make any necessary preparations like tying down trampolines and securing loose objects like wheelie bins

Kia haumaru, stay safe

— MetService (@MetService) December 8, 2023

Heavy Rain Warning - Orange

• Westland about and south of Otira: 12hrs from 7pm Saturday 9 Dec - 7am Sunday, 10 December
• Headwaters of the Canterbury lakes and rivers about and south of Arthur’s Pass: 11hrs from 9pm Saturday 9 Dec - 8am Sunday 10 December
• Headwaters of the Otago lakes and rivers: 11hrs from 3pm Saturday 9 December - 2am Sunday 10 December
• Fiordland: 12hrs from noon - midnight Saturday 9 December

Strong Wind Warning - Orange

• Canterbury High Country: 14hrs from 3pm Saturday 9 December - 5am Sunday 10 December
• Otago (excluding North Otago), Southland, Stewart Island and Fiordland: 11hrs from noon - 11pm Saturday 9 December

Heavy Rain Watch

• Buller and the ranges of Westland north of Otira: 8hrs from 2am - 10am Sunday 10 December

Strong Wind Watch

• Wairarapa south of Masterton, Wellington, the Marlborough Sounds, Kaikoura coast and ranges: 10hrs from 2am - noon Sunday 10 December
• North Otago, Canterbury Plains including Christchurch: 12hrs from 3pm Saturday 9 Dec - 3am Sunday 10 December