Christchurch's quake-damaged stormwater and sewerage system is struggling as the latest storm dumps heavy rain, and snow across the city, closing schools and roads.
The morning's snow and sleet has now cleared over the city but is set to return warn forecasters.
A water main burst in the central city this morning.
Many Christchurch schools closed for the day while others advised parents to keep children at home. The Education Ministry said a total of 71 schools closed across Canterbury today, and about 30 in Otago and Southland.
Buses on Cashmere and Huntsbury hill routes were cancelled and Dyers Pass Rd closed from the Sign of the Takahe on Cashmere to Governors Bay after several motorists became stuck.
At 9.30am a burst water main erupted out of St Asaph St between Manchester and Madras streets forcing the road to be closed.
The Christchurch City Council has warned that some flooded roads and parks could contain contaminated water,.
A council spokesman said earthquake-damaged wastewater systems are fragile in parts of the city and have been blocked by rain.
''It's possible flooded roads and parks may be contaminated, so avoid the water where possible or make sure you wash your hands and remove and wash any clothing that gets wet.''
Hill roads are currently extremely dangerous for motorists and should be avoided until later this afternoon, the council said.
Power outtages have been seen in Arthurs Pass, Hororata, and South Canterbury.
An Intercity bus from Christchurch to Blenheim was stranded in Kaikoura overnight when State Highway 1 was closed. The 19 passengers were put up in Kaikoura backpackers and motels.
MetService public weather services manager Ramon Oosterkamp said the large snow-bearing cloud over the city and surrounds was slowly moving north.
"We can see the back edge of it on the radar out there beyond Banks Peninsula and down to the south of Ashburton.
"Once that moves through you'll be back to the more showery stuff and probably that sleety cold rain."
However, heavy snow showers were still likely during the afternoon, particularly above 100m.
The expected easing of the snow over Christchurch did not mark the end of the polar blast though, he said.
More snow and sleet was expected to very low levels overnight and tomorrow before clearing late in the day.
Many sporting fixtures have been cancelled including all Canterbury Rugby League games, all lower grade Mainland Football games and Future Ferns netball this evening. All metropolitan club rugby has been called off except division one. Canterbury Hockey is set to announce cancellations later today.
Christchurch City Council teams are currently helping motorists stuck on the road and are clearing the snow while Environment Canterbury has relaxed clean air for those needing to use logburners to keep warm.
The council asked motorists to slow down and drive with care, especially through flooded areas, as the waves caused by vehicles could cause further flooding to already at-risk properties.
Neither Christchurch police nor fire service have been called to any weather-related incidents since the snow began falling over the city and St John said its ambulance service's workload was no higher than normal.
Some flights in and out of Christchurch airport have been delayed or cancelled this morning.
Snow, sleet and heavy rain has caused havoc across the Hurunui District overnight, with gale force winds bringing down power lines and trees.
Porters Pass, the Lewis Pass and the Lindis Pass remain closed this morning, and chains are essential over Arthurs Pass.
DUNEDIN SNOW DIRSUPTS
Road closures hampered Dunedin travelers this morning, with the Dunedin City Council reporting more than 30 roads were closed due to storm debris, flooding, snow, and unsafe conditions.
State highway 1 at Kilmog Hill was closed for a period of time this morning due to ice, preventing travel north of the region.
MORE TO COME
MetService spokesman Daniel Corbett warned the "crunch time" in the three-day-plus storm would not pass until this afternoon.
In Canterbury, torrential rain caused flooding in several Leeston homes, and closed schools yesterday morning when a creek bed burst its banks, flooding about eight homes.
Schools remain closed today.
Flooding was also reported in Mosgiel, Port Chalmers and Ashburton.
Waimakariri Civil Defence was on standby overnight as the Cust and Dockey rivers near Rangiora threatened to break their banks.
Dozens of large trees and several power lines had been brought down by gale-force winds in the Hurunui district, closing roads and cutting power.
Conditions were so bad, crews were being prevented from going to clear roads.
Power had also been cut in Naseby in Central Otago, Middlemarch, and Fairlie in Canterbury.
For inland parts of North Canterbury, Niwa models were predicting 50 to 100 centimetres of snow would fall, but forecasts were for considerably less towards the coast.
- The Press