Weather: Cold frosty snap across the South Island with temperatures plummeting below zero

White frost coats Christchurch's Hagley Park this morning. Photo / George Heard

A balmy start to the week across the country was nothing but a brief blip, with frost felt across the South Island this morning.

Christchurch residents woke up to a crisp, clear morning with thick frost coating parts of the city.

Some locals may have been late to work this morning trying to defrost vehicles, as temperatures dipped to -2C in places.

A cold start for Christchurch with frost in Hagley Park on Wednesday morning. Photo / George Heard

MetService meteorologist John Law said Christchurch airport had -5C overnight.

Law said although it was an “unusually warm” start to the week, colder temperatures are typical for this time of year.

“We had that really mild start to the week that was unusual, with that air coming in from the north and the west. As our winds swung around towards that southerly direction, we saw that cold air coming up,” Law said.

“So a real cold and frosty start for many parts of Christchurch.”

A cold commuter in Christchurch's Hagley Park on Wednesday morning. Photo / George Heard

The coldest place in the South Island was Lake Tekapo, where temperatures dropped to -7C.

Law said the cold snap shouldn’t last too long, with temperatures likely to pick up slightly over the next few days.

“I think for many of us, last night was probably one of the colder ones,” he said.

“Once we head in towards Thursday and Friday, our temperatures actually start to pick up again as we start finding some more unsettled weather back towards us.”

Law said although temperatures are set to get warmer, tonight will be another cold one for Christchurch.