Snow replaces scorching heat in South Island

South Islanders are swapping their sunhats for puffer jackets as fresh snow replaces scorching heat.

The extreme change comes after a sweltering start to the week that brought record-breaking temperatures.

General manager of operations at Mt Hutt Ski Area James Urquhart says he saw a massive drop in temperatures this week. 

"We've gone from 37C two days ago to 0C today."

The ski ki field woke to 10cms of fresh powder on Friday, right in the middle of summer. 

"Not a bad dumping for this time of year that's for sure," Urquhart says.

"The mountain's covered in white and it looks good."

The icy blast arrived abruptly after eastern parts of the South Island sizzled in record-breaking temperatures just a few days ago.

Ashburton reaching 39C on Tuesday, breaking a 65-year record.

Metservice Meteorologist Angus Hines says there's been a drop of more than 20C.

"How about Christchurch 3pm Wednesday 34.8C and 3pm Thursday 11C to give you an idea of the fall away."

The drop in temperature was clear at a deserted Sumner Beach that only days ago was bustling with overheated beachgoers.

"The weather is coming from pretty far south of the country sitting down there over those cold waters and the south that's why you feel the temp drop," says Hines.