The Otago Regional Council says it will be monitoring river levels over the weekend, with heavy rain forecast for Dunedin and other parts of the region.
The ORC announcement comes after heavy rain last weekend pushed up river levels in the South.
MetService today said a burst of heavy rain could hit East and North Otago tomorrow, while snow would develop early tomorrow and become heavy at high altitudes in the northern ranges of Otago and the South Canterbury high country.
ORC director engineering, hazards and science Gavin Palmer said while it was too early to predict whether river levels might rise tomorrow, the council would be monitoring them closely for the next 48 hours at least.
WeatherWatch forecaster Philip Duncan said the "incredibly fast development" of a low meant a rough weekend was in store for some places.
"While a large low often means the rain clouds get fractured and broken up, the low has enough energy to bring localised flash flooding to some areas," he said.
Mr Duncan expected to see very wet easterlies into Otago and parts of Canterbury on Sunday, and wet west-to-northwest winds in the North Island.
#Dunedin & eastern Otago could see heavy rain on Saturday. Snow in the high country https://t.co/nsWPDehsQA pic.twitter.com/FBUrBAWX0y
— Chester Lampkin (@chesterlampkin) May 27, 2016
"The flipside means the west of the South Island may be mostly dry on Sunday but heavy rain could still form over the dry eastern North Island as a colder southerly sweeps in," he said.
"Rain may also become heavy in Dunedin and coastal Otago this weekend -- with set-in rain lasting a day or so, so those concerned with flooding may want to keep a close eye on the movements of this low."
Up to 30cm of snow was forecast above 1200m during Saturday morning and early afternoon, with lesser amounts down to 600 metres.
Meanwhile, MetService meteorologist Derek Holland said the unsettled weather would hit much of the country.
"There was a lull in weather overnight and a brief ridge is crossing the country this morning but then another weather system is coming through over the weekend which will bring rain to many parts of the country," he said.
MetService has a heavy rain warning in place for parts of central New Zealand from this evening to tomorrow morning.
Mount Taranaki, Buller, Nelson and northwestern parts of Marlborough will be the worst affected with between 70 to 100mm of rain possible overnight.
Thunderstorms and northwest gales were also possible in parts of the North Island, Mr Holland said.
"The most severe weather will be Saturday morning. Later on in the day it will still be windy but not as severe.
"Sunday will be showery with rain over the North Island and northwest gales for a time over the northern half of the North Island."
Mr Holland said there wasn't a "place to be this weekend". "Parts of the South Island won't be as windy but it's all not great."
Unsettled weather was likely to continue into early next week, according to MetService.
Main centres outlook
Dunedin: Today: Fine then cloud developing in the afternoon. Light winds. High 12C. Saturday: Rain developing in the morning. Cold southwesterlies developing. High 10C. Sunday: Occasional showers. Cold southwesterlies. High 10C.
Auckland: Today: Sunny spells with possible showers. Westerlies turn northerly. High 19C. Saturday: Heavy early rain then showers. Strong gusty northwest. High 20C. Sunday: Few showers then rain. Northwesterlies. High 19C.
Hamilton: Today: Cloudy periods and a few showers. Westerlies turn northerly. High 17C. Saturday: Periods of rain, some heavy and possible thunder. Northwest. High 19C. Sunday: Showers, some heavy. Northwest easing. High 18C.
Wellington: Today: A mostly sunny day. Rain at night. Northerlies. High 16C. Saturday: Rain, possibly heavy and thundery. Strong gusty northwest. High 16C. Sunday: Occasional showers. Northwest changing southerly. High 14C.
Christchurch: Today: Mainly fine. Patchy drizzle and northeast develop at night. High 12C. Saturday: Rain, heavy at first. Cold southerlies. High 11C. Sunday: Occasional showers. Cold southwesterlies. High 9C.
- Source: MetService
