South Island set to swelter - MetService

South Islanders will get to bask in summer-like conditions in the coming days as a northwesterly brings with it temperatures nearing 30C.

Just how hot it gets remains to be seen, with MetService expecting a peak of up to 26C for Central Otago's Alexandra, while National Institute of Water and Atmospheric Research [Niwa] forecasts 28C.

However, MetService duty meteorologist Lisa Murray said North Islanders wouldn't get those temperatures but did it expect it to be warm with a brief period of showers over the long weekend.

"It's not like were going to heat up straight away. What's happening is there's a northwesterly flow over particularly the South Island. Those eastern areas in that northwesterly flow, they get that foehn effect wind and it does heat things up.

"If you've ever lived in Christchurch or Dunedin you know in northwesterlies you tend to get warmer weather because not only are you getting sheltering from the ranges where all the cloud and rain will fall ... but you have warmer air as well."

Thursday and Friday are when things are expected to heat up, with Christchurch forecast for 20C on Thursday and 19C on Friday. Dunedin will be warmer on Friday with 23C but nothing compared to Alexandra's 26C for Thursday.

Niwa dubbed the influx of warm weather as the #southernspringsizzle in its tweets earlier today.

Our model is forecasting maximum temperatures into the late 20s to near 30 across interior Otago. Check out Alexandra, for instance! pic.twitter.com/NJEbxcd3a5

— NIWA Weather (@NiwaWeather) October 16, 2017

Murray said MetService had chalked up 27C for Alexandra but brought it down a temperature due to high cloud expected on Thursday.

But the warm weather will be brief with most South Island temperatures expected to drop back into the teens on Saturday.

There was wet weather moving up the country on Friday however it will weaken as it makes its way north.

"It does gradually move up the country so by Saturday evening it's affecting from around Waikato, Taranaki ... Saturday night it moves into the Auckland region."

The weather will then ease with most waking up to sunny skies on Sunday morning.

Up until the weekend, most of the country is expected to bask in sunny skies before the rain makes itself present.

WARMING UP

Thursday Friday Saturday
Auckland 17 18 18
Coromandel 18 19 18
Gisborne 14 16 22
Napier 16 17 21
Masterton 18 22 19
Christchurch 20 19 16
Dunedin 20 23 16
Alexandra 26 25 18