Dunedin could be hit by as many as eight significant snowfalls this winter as El Nino looks set to bring a raft of polar-chilled southwesterlies to the city.
A storm blasting Antarctic weather over Otago closed roads, cut power and blanketed towns in snow yesterday.
The Antarctic blast closed the main northern route into Dunedin until lunchtime as authorities waited for snow and ice to clear.
Inland Otago roads were treacherous, with warnings in place on main routes throughout the day.
With temperatures hovering in the low single digits, electricity workers across the region battled to restore power after it was cut by snow and wind in parts of Dunedin and Central Otago.
The most dramatic incident was in Tainui in Dunedin where a power transformer exploded ''with a sound like a bomb'' after being hit by lightning about 5am.
In neighbouring St Kilda, high winds toppled a large brick chimney at Forbury Park raceway.
Dunedin hydrologist Dave Stewart said while the city's snow was ''seasonally normal'', he warned this winter's expected El Nino weather pattern could lead to a far higher incidence of snow days than what Dunedin had experienced in recent years.
An El Nino weather pattern tended to bring increased southwesterlies from the polar regions, which were likely to lead to the increased snowfall across the city, he said.
MetService meteorologist Georgina Griffiths said predicting snow days was difficult.
A combination of moisture, cold temperatures and uplift was needed, and could not be predicted accurately.
But she too said the South was likely to experience colder-than-normal weather during the coming winter months.
El Nino's main impact was expected in spring, with significantly colder temperatures in the South than those experienced over the past few years, she said.
Thunderstorms running up the east coast brought lightning strikes, with 13 recorded strikes on the Otago Peninsula between Sunday evening and noon yesterday.
Aurora Energy said lightning damage to transformers caused power cuts in Musselburgh.
Severe winds downed lines in Port Chalmers and on the Otago Peninsula.
Heavy snow caused power outages in Central Otago.
Power had been restored to most affected parts yesterday.
Mr Stewart said Dunedin's roads and city could have been hit far harder than they were.
An unexpected temperature rise early yesterday meant Dunedin's snowfall was considerably less than expected, much of it washed away by rain.
While snow began falling steadily in Dunedin about 8pm on Sunday, settling at sea level by 11pm, the forecast heavy snowfall never eventuated as temperatures rose to about 3degC during the night.
MetService meteorologist John Law said elevated areas had the heaviest snowfalls, with 25cm at Clarks Junction between Sunday evening and noon yesterday. Dunedin's hill suburbs received 10cm of snow, with just 3cm at sea level.
State Highway 87 between Outram and Kyeburn remained closed last night.
Several Dunedin bus routes were disrupted.
