MetService had forecast severe morning frost in Dunedin with a low of 3°C.
The Otago Regional Council advised that the Pine Hill bus (Route 5/6) is affected this morning and can't service the Dalmore loop due to ice.
Several areas in Central Otago have recorded temperatures below freezing, with Ranfurly recording -6°C, Omakau -5°C Alexandra -4°C, Cromwell -1°C and Roxburgh on 0°C at 6am.
The Central Otago District Council says the roads are dry but there are patches of fog in low-lying areas.
Crews have gritted trouble spots. Caution advised particularly around daybreak: take care in shaded spots and bridge decks.
In the Queenstown Lakes District, the grass is crunchy underfoot and Jack Frost has done the rounds, a spokeswoman for the district council said.
The temperature in Glenorchy was 1.2°, but into the negatives across the rest of the district with Wānaka and Arrowtown seeing lows of -4°C.
Grit has been applied to frosty sections on the Crown Range Road, linking Queenstown and Wānaka, Arrow Junction and from Fernhill roundabout to Dart River Bridge.
"Watch out for patches of fog as day breaks too. Crews are out gritting problem areas and patrolling the network.
"Keep those speeds down and watch for ice and areas of loose grit."
Crash in North Otago
Emergency services were called to a crash on State Highway 83 near Omarama in North Otago.
Police said the incident was reported about 8pm yesterday.
A person had minor injuries after a car appeared to have rolled onto its side, they said.