Air New Zealand cancelled the remainder of today's flights to and from Christchurch with customers to be booked on the next available service "once flights are operating again'', the airline's website says.
Some other airlines were operating and Christchurch Airport remained open.
Staff would provide food and blankets to stranded passengers.
Mainpower engineering manager Peter Hurford said he was confident another 2000 houses without power in the Kaikoura district would be back online by this evening but there were a few hundred homes in rural and remote areas that would not have their services repaired until tomorrow.
The University of Canterbury will not reopen until midday tomorrow.
St John in Canterbury said it had a steady workload today and reported three incidents in which people fell from ladders or roofs
"We urge everyone to be careful when clearing roofs, drains and satellite dishes of snow,'' said Chris Haines, St John regional operations manager South Island
"Our main concern now is conditions overnight and especially tomorrow morning. If the weather stays very cold overnight (as it likely will) then there is the potential for conditions to turn very icy.
"St John encourages everyone to be very careful tonight and tomorrow when travelling, especially driving or walking, and limit it to only necessary travel,'' he said in a statement.
Canterbury police warned motorists to be "extra cautious'' of ice on roads tonight and tomorrow morning.
"Although snow may ease off in the coming hours, road conditions are likely to remain challenging through the night,'' police said.
Temperatures are expected to drop to minus 4C in Ashburton tonight, which could turn into slush on roads.
Storms have started to ease at Nelson and Tasman, where gusts above 100km/h were expected throughout the day.
Alpine passes have been shut and inland routes are blocked, including Arthur's Pass and the Lewis Pass.
Film maker Geoff Mackley, who is trapped at Arthur's Pass, said trees had been destroyed and power lines were down.
"I've never seen it so bad,'' he said.
Schools around the South Island were closed.
The West Coast copped wild weather and 11 homes at Coal Creek were evacuated, as well as that of a family of nine forced to flee their flooded Greymouth house.
Water was 45cm deep through the property when the Runanga Volunteer Fire Brigade moved the Stollery family to higher ground.
Roofs were lifted by near gale-force winds at Greymouth.
New Zealand Post suspended its mail delivery in Greymouth and outlying areas.
Meanwhile, flights have resumed at Dunedin airport where 10 were cancelled this morning.
The city centre has remained relatively snow-free while the hills and outlying suburbs have borne the brunt of the icy blast.
