Amid a flurry of snow yesterday, unseasonably cold weather descended on much of the South, where it is expected to stay chilly for the rest of the week.
MetService meteorologist Georgina Griffiths said this kind of weather was ''typically a late-April or May thing''.
Meteorologist Peter Little said rain was expected to disappear as the week went on but the cold weather would persist - a ''good recipe'' for frost.
As the snow began to fall yesterday morning,, MetService issued a ''severe weather warning'' for Southland and southern parts of Fiordland and Otago, especially the Clutha area.
Transport authorities urged travellers to be cautious.
MetService reported inland Southland and southern Otago had received about 10cm-15cm of snow.
Mr Little said 15cm of snow was reported at Jollies Pass, Northern Southland, and the Homer Tunnel, near Milford.
In many other centres, including Queenstown, Invercargill, and Dunedin, snow did not settle, he said.
Te Anau residents woke to about 10cm of snow yesterday, most of which had cleared by 4pm.
Coronet Peak ski area had 15cm of snow yesterday, Treble Cone about 10cm and 50cm-70cm drifts were reported at Cardrona Alpine Ski Resort.
Niwa climate scientist Gregor Macara said the last time there was significant early April snowfall at Coronet Peak was in 2009, when about 10cm fell.
Despite the snowy conditions, Senior Sergeant Ben Butterfield, of Dunedin District Command Centre, said police had not been notified of any serious incidents as a result of the weather.
However, there had been many minor incidents where vehicles slipped off the road.
''Our advice is that if you don't need to drive, then don't.''
The New Zealand Transport Agency issued an area warning for roads in Otago, Southland and Fiordland yesterday, but did not report any road closures.
In Dunedin, Three Mile Hill road was closed at 3.40pm yesterday, and remained closed last night.
Queenstown International Airport was temporarily out of commission yesterday because of low visibility and snow on the runway, communications manager Jen Andrews said.
''One [flight] was diverted to Dunedin, and a couple to Christchurch, and others were cancelled at their origin.''
In total, 22 of 34 scheduled flights were cancelled, but operations were running by about 4pm, she said.
At Dunedin International Airport, several flights were delayed last night and one JetStar flight to Auckland was cancelled because of hail and sleet on the runway, an airport spokesman said.
The Otago Regional Council reported yesterday afternoon the Ross Creek, Brockville and Halfway Bush bus services were not travelling their full routes because of snow and ice. This advice had not been lifted late last night.
Federated Farmers Otago president Stephen Korteweg said he had not heard of Otago farmers having problems as a result of the sudden cold snap.
''We had plenty of warning,'' he said.
The Queenstown and Dunedin maximum averages for April were 15.7degC and 15.4degC respectively, while yesterday's respective temperatures were 3degC and 7degC.
Ms Griffiths said because of the ''unseasonably warm'' weather enjoyed by the South Island last week, yesterday's weather was ''quite a shock to the system''.