Record-breaking temperatures are about envelop eastern regions over the coming 48 hours, while potentially damaging winds, heavy snow and rain are starting to bear down on the south.

A swathe of severe weather warnings and watches are now in force for much of the South Island as heavy rain and strong wind start lashing the deep south and western regions. Up to 29 hours of rain is expected in some parts with the wild weather not expected to let up until Friday.

There is even a threat of heavy snow for alpine regions in Canterbury and Otago as a polar blast sweeps up the island on Friday ahead of the school holidays.

But as the stormy weather hits, eastern centres are set to swelter in summer-like temperatures, with 25C forecast for Blenheim today and Napier expected to hit 26C tomorrow.

MetService meteorologist Andrew James said the weather was a “real typical kind of El Nino spring setup”.

“So it is a flip of the switch from what we’ve had, over the past while the North Island was getting all the wet stuff out in the northeast.”

During the approach to summer, eastern parts of both islands were expected to get more warm Foehn winds.

James said there was likely to be big temperature differences from west to east, with the east of New Zealand experiencing some hot days this week, left over from northwesterly winds.

By the time the air travelled to the eastern side of the country, it would have a less humid and much drier feel.

“It brings down that famous Canterbury northwester, a very strong, dry, dusty warm wind.

“Christchurch is looking like a high of 23 today and 22 tomorrow, and in the North Island too, there are a few places where there will be a warmer average temperatures.

“Napier is looking to hit 26 tomorrow.”

James said those on the west were likely to be battered by wind and rain instead of heat this week.

Niwa Weather warned that another round of potentially damaging wind is on the cards today in parts of the South Island.

Those living in areas at higher elevations would have the highest speeds and greatest risk for damage and power cuts, but some lower elevations might also see gusts over more than 100 km/h, especially across Southland and Otago.

Strong wind warnings are now in force for Fiordland, Southland, Stewart Island, Otago, Canterbury High Country and Christchurch including Banks Peninsula for the coming day.

Niwa said severe gale northwesterlies could reach gusts of 140km/h in exposed places tomorrow.

It said strong wind gusts could damage trees, powerlines and unsecured structures. Driving may become hazardous, especially for those in high-sided vehicles and motorcycles.

Meanwhile, on the West Coast, up to 350mm of rain around the ranges is expected in parts of Westland and 100 to 150mm nearer to the coast. A warning is in place from 8pm tonight for 24 hours.

Thunderstorms are possible alongside peak rates of 15 to 25mm/h of rain today and tomorrow in the ranges.

MetService warned that heavy rain may cause streams and rivers to rise rapidly alongside the possibility of surface flooding and slips, and driving conditions may be hazardous.

A moist northwesterly flow will bring warning amounts of rain for Fiordland and Westland, and there’s a high chance of severe gales for Canterbury, Otago, Southland and Fiordland.

Through Thursday, the front will move north, bringing more wind and rain to Fiordland, Westland, and the headwaters of the Canterbury and Otago lakes and rivers.

MetService said it was also possible heavy snow could affect higher parts of Otago and Canterbury on Friday and Saturday as a polar blast swept up the island.

Temperatures in centres are expected to drop markedly with Christchurch expected to reach just 10C at the weekend.