Weather: More lightning in store for New Zealand as storm hammers down

New Zealand faces another round of lightning strikes as the big Southern Ocean storm continues to churn just near Stewart Island.

It will drive a colder change up New Zealand, with winds still into gale-force through a number of regions.

It also means heavy showers for western areas as well as the risk of thunder for many places in New Zealand.

"There is a moderate risk of thunderstorms from Taranaki to Kapiti, also western Nelson to Fiordland, and for southern parts of Southland and Clutha," MetService says.

"A broad low risk of thunderstorms extends from the upper South Island to areas near the Alps, and to the lower South Island. A low risk of thunderstorms spreads over Waitomo and Waikato this evening."

A MetService graphic shows the showers coming in from the west.

"Don't be fooled by the word shower - some of these are quite intense and even firing off some lightning," MetService warns.

Over 90 percent of New Zealand will have below-average temperatures today as the storm near Stewart Island dredges up a cold change.

"Single-digit highs are likely through some parts of Southland, Otago and Fiordland although it doesn't look quite as cold as today could have been. Most main centres will make highs into the double digits - but not all may make it to the teens," WeatherWatch says.

"Auckland has a high of around 19C or 20C today, about 8C lower than yesterday. Christchurch has a high of around 18C today, this is about 10+C cooler than yesterday."

Winds may reach severe gale strength around the Cook Strait and the lower Southern Alps/Fiordland, and MetService warns "high-energy heavy swells" feature along the western coastlines Wednesday into Thursday.