Orange heavy rain warnings have been issued for the upper North Island and upper South Island as a strong, moist front barrels towards New Zealand.
MetService said a front preceded by a strong moist northerly flow was forecast to move east across the country on Friday and Saturday morning.
Areas saturated by heavy rain late last month were in the firing line again, with Nelson, Tasman, parts of Marlborough and southern Taranaki set for a drenching over the next two days.
Nelson has a high chance of being upgraded to a red level heavy rain warning, MetService said.
“Dangerous river conditions, flooding, and slips likely. Dangerous driving conditions and road closures are expected.”
Northland, Auckland, the Coromandel Peninsula and the Waikato region were also expected be lashed by heavy rain, with up to 110mm possible in some areas.
MetService said streams and rivers could rise rapidly and that surface flooding, slips, and difficult driving conditions were possible.
Heavy rain watches were in force for the southern Waikato, Bay of Plenty, and northern Taranaki, with strong wind watches for Taihape, Whanganui, and Banks Peninsula.
MetService meteorologist Michael Pawley said heavy rain would be falling in areas that had seen “significant rainfall” recently.
“Parts of Nelson have already received an average years’ worth of rain since January. The risk is that already saturated soil and damaged infrastructure will struggle to cope with an additional burst of rain.”
He urged drivers to take it easy on the roads and consider changing the timing of travel.
“Consider timing your journey for when the rain eases if you’re traveling though affected areas.”
Forecast ‘isn’t looking the best’ – Civil Defence
Nelson Tasman Civil Defence said the forecast for Friday and Saturday “isn’t looking the best”.
“The hydrology team are looking into the potential impact for our region, and we will provide updates as soon as they are available.
“If you have previously been affected over the past couple of weeks, we suggest that you start preparing for more rain.”
Marlborough residents have been advised to “be ready and be prepared” by Civil Defence after MetService issued an orange heavy rain warning for the region for Friday through Saturday.
Marlborough Emergency Management group manager Matt Kerr said there was a risk some situations in already fragile areas could be exacerbated.
“We want to get advice out to our communities including Spring Creek, Rārangi, Northbank, Kenepuru Rd and Port Underwood that readiness remains important.
“Although Friday evening’s weather is predicted to move through quickly, we encourage people to take stock of their preparedness, remain in touch with friends and whānau and to have plans in place for safety and support.”
Full list of weather warnings and watches
Orange Heavy Rain Warning
Northland and Auckland (excluding Great Barrier Island) – 16 hours from 6am Friday
Great Barrier Island, Coromandel Peninsula and Waikato – 15 hours from 11am Friday
Taranaki Maunga – 13 hours from 11am Friday
Tasman District northwest of Motueka – 12 hours from 9am Friday
Nelson (about and southeast of Motueka and north of Lake Rotoroa), Marlborough (northwest of Awatere Valley) – 16 hours from 9am Friday
Orange Strong Wind Warning
Taranaki south of the Maunga – 11 hours from 12pm Friday
Heavy Rain Watch
Bay of Plenty including Rotorua – 16 hours from 1pm Friday
Waikato, Taumarunui and Taupō – 12 hours from 2pm Friday
Taranaki north of the Maunga – 13 hours from 11am Friday
Strong Wind Watch
Taihape and Whanganui – 12 hours from 12pm Friday
Banks Peninsula – 10 hours from 6pm Friday