Black ice made driving difficult for many in the South yesterday.
A police spokeswoman said there were at least 15 ice-related crashes in the region - one in Arrowtown, two in South Otago and the rest in Dunedin.
A vehicle hit ice and rolled off the Kaitangata Highway about 6.45am, she said.
St John spokesman Ian Henderson said a man, in his 20s, sustained moderate injuries and was taken by ambulance to Clutha Health First.
An ambulance was called but not required when a car left Kaka Point Rd in South Otago about 3.15pm.
Willowbank Station Officer Phillip De Rooy said he saw three ice-related crashes on the Northern Motorway before 9.30am yesterday.
The first crash was at Pigeon Flat about 7.30am, when a light truck hit ice and "teetered on the edge'' of the motorway.
Mr Henderson said the male driver was uninjured.
In another motorway crash, a man was driving a Toyota car north and "lost it in the ice'' causing a "slow speed roll over'' about 9.20am.
When the crew arrived, the car was on its roof in a bush area on the side of the motorway.
Mr Henderson said the male driver was uninjured.
At the crash scene, another car which had overturned south of Butlers Bridge about 10 minutes earlier was towed past.
"Winter has been a bit slow coming, and the ice has caught people unaware,'' Mr De Rooy said.
A police spokeswoman said a ute crashed into a Northern Motorway barrier at Pine Hill about noon yesterday and a vehicle skidded on ice and hit a barrier on the Wharf St overbridge about 6.45am.
Mr Henderson said a woman sustained moderate injuries and was taken by ambulance to the Dunedin Hospital emergency department.
A police spokeswoman said a car "spun out'' on Saddle Hill Rd about 7am and blocked an off-ramp.
Mr Henderson said a man, in his 20s, sustained minor injuries and was taken by ambulance to the Dunedin Hospital emergency department.
A police spokesman said the driver of a small truck going down Filleul St lost control after hitting ice.
The truck spun and hit a Mercedes car parked in the street about 9.30am.
MetService communications meteorologist Lisa Murray said temperatures were forecast to "plummet'' across Otago and be colder this morning than yesterday.
Motorists should prepare for more icy driving conditions.
Dunedin airport spokeswoman Megan Crawford said ice on the runway caused two flights to be cancelled.
"The first flight out went at 11.15am, and that was the service due to go out at 6.20am to Wellington and then Auckland.''
Ms Murray said the temperature plummeted to -6degC at Dunedin airport at 9am yesterday.
Niwa climate scientist Gregor Macara said the lowest recorded temperature in Musselburgh, Dunedin yesterday was 0.1degC between 6am and 7am.
The minimum temperatures in Otago yesterday included Ranfurly -7.2degC, Middlemarch -6.1degC, Lauder -5.5degC, Clyde -4.9degC, Balclutha -4.8°C, Alexandra -3.3degC, Wanaka -3.3degC and Queenstown -1.9degC.
"The temperatures are not exceptionally cold for this time of year. They are particularly notable because of the exceptional warmth we have been experiencing for this time of year, and heavy frosts like these have been a rarity.''
Dunedin City Council asset and commercial manager Merrin McCrory said Downer staff were gritting roads from 3am yesterday.
A total of 12 accidents were reported - four on state highways and eight on council roads.
Most of the crashes on city council roads occurred in areas which were not gritted, including two crashes on Wharf St.
