Heavy rain is on the way for several regions, including Westland - where flooding caused major road damage last month. Photo: Supplied / Allan Dick
Drivers are being urged to take extra care on South Island roads, and warned that roads could close, as heavy rain and wind warnings spread orange and yellow across the map.
An intense front is expected to move north over the South Island and then up the lower North Island, with heavy rain and severe gales likely for many places between Sunday morning and Monday, MetService forecasters said.
The west of the South Island is expected to be particularly hard hit, after flooding and slips closed major roads there for almost half of last month.
As much as 250mm of rain could fall in some Westland areas between 6am and 9pm on Sunday, MetService said, with possible thunderstorms and peak rainfall up to 35mm per hour. Through Sunday and into early Monday the headwaters of Canterbury lakes and rivers could also expect up to 250mm, parts of the Grey and Buller Districts could expect up to 160mm, and some Tasman areas could expect up to 150mm of rain.
Waterways could rise rapidly, with surface flooding, localised flooding, slips and difficult driving conditions all possible.
In the North Island, heavy rain could hit the Tararua Range, from late Sunday into Monday, with up to 100mm of rain possible.
The NZ Transport Agency (NZTA) said State Highway 6 - the main corridor up the west side of Te Waipounamu - could shut at short notice if the storms create fresh slips or rockfalls.
Rockfall protection work was still being carried out on the highway, as part of the clean-up from the November flooding, NZTA central South Island system manager Mark Pinner said, and there were concerns that heavy rain could trigger more.
"We are monitoring the area around Epitaph Slip this weekend, and if rainfall does intensify on Sunday, we may close that section of route ... either because of fresh activity, or as a precautionary approach. This will be the largest rainfall since we had the original issues there," Pinner said.
In the Lower North Island, the weather is expected to be in full swing during peak traffic on Monday morning, NZTA warned.
MetService warned that people should stay up to date with the latest forecasts.
Updated Severe Weather Watches and Warnings have been issued for the passage of an active front tomorrow and into Monday morning.
— MetService (@MetService) December 6, 2024
Warnings for heavy rain have been issued for the West Coast and adjacent ranges. In addition, strong wind warnings have been issued for much of the… pic.twitter.com/zoV91ULUXl
Meanwhile, severe gales are forecast from Sunday, for the Canterbury High Country, including for State Highway 73 where the Bridge Hill scrub fire is still burning - and for the Marlborough Sounds, Kaikōura coast and ranges, Wellington and up into south Wairarapa.
Strong winds watches had also been issued for winds possibly approaching severe gales for much of the rest of the South Island and further north, including: Stewart Island, Fiordland, Southland, Otago, the Canterbury Plains, Banks Peninsula, wider Marlborough region, Tararua District, north Wairarapa, and southern Hawke's Bay.
NZTA warned these highways are expected to be affected by the bad weather between Sunday and Monday:
South Island:
- State Highway 6: Westland, through the Buller Gorge, and from Blenheim to Nelson
- State Highway 1: Marlborough
- State Highway 63: between Wairau Valley and St Arnaud
- State Highway 60: near Tākaka
- State Highway 6: through the Buller Gorge.
Lower North Island:
- State Highway 1, 2, 58 and 59 in Wellington, the Hutt Valley, Porirua, and Kāpiti Coast
- State Highway 2 and State Highway 53, in Wairarapa, including the Remutaka Hill.
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