After days of warm weather parts of the South Island woke to snow on Tuesday with even coastal areas getting a smattering on the first day of spring.
"We've got a situation with some north-westerlies aloft and southerlies pushing in. We're getting snow levels pretty low, at 200 metres in Canterbury at the moment with possible flurries getting down to 100 [metres]," MetService meteorologist Tam Pletzer said.
MetService issued snow warnings for the Lewis, Arthurs, Porters, Lindis and Haast passes, as well as for the Crown Range and Milford Rds.
The Queenstown Lakes District Council is requiring chains to be fitted on vehicles driving over the Crown Range Rd, and for them to be carried on a number of other routes.
Visibility is low and motorists are warned of debris on roads after strong overnight winds, the council said in a statement.
"Our crews are working to clear this but please take extra care and slow down," the statement said. "Heavy rain has also caused some minor rockfalls through the Kawarau Gorge and there's heavy snow further afield too.
"If you're planning to head over the Lindis Pass or to Haast, make sure you have your chains and you know how to fit them if required."
The snow and heavy rain near Aoraki/Mt Cook overnight helped firefighters battling to slow a huge scrub fire burning since Sunday, dampening flammable materials in the fire's path. The Milford Rd is closed from East Gate to West Gate due to snow.
There was snow on the Te Anau side of the Homer Tunnel but none on the western side, the NZ Transport Agency said. The road was expected to reopen before 10am.
NZTA says there's snow and ice on State Highway 79 between Fairlie and Rangitata and the agency urged drivers to take extra care.
NIWA meteorologist Chris Brandolino said overall spring was expected to be warmer than usual for all of Aotearoa.
Rainfall is also expected to be near or below normal in the South Island which could be an issue for the fire season, he said.