Thunderstorms are predicted for much of North Island and South Island today in what will be a sticky and possibly wet Thursday.
It comes as the National Institute of Water and Atmospheric Research says higher pressure than normal was forecast to bring well above average temperatures to New Zealand over the weekend and leading into next week.
Some towns could reach 30C in that time.
A severe thunderstorm watch is in place about central parts of the North Island this afternoon and evening, from the Kaimai Range and the ranges of Bay of Plenty and Gisborne down through the central North Island high country to the Tararua Range.
That could produce localised downpours of 25 to 40mm or possibly more, and hail possibly larger than 20mm.
MetService has forecast a weakening front will approach the West Coast of the South Island bringing rain and a moderate risk of thunderstorms to northwest Nelson, coastal parts of Buller and northern Westland this morning.
"Meanwhile, showers are expected over the northeast of the North Island during Thursday morning and there is a low risk of isolated thunderstorms developing about Bay of Plenty, eastern Taupō, Gisborne and northern Hawke's Bay towards midday," MetService said.
There was also a "moderate to high risk" of thunderstorms during the afternoon and evening from Waikato, southern Coromandel and inland Bay of Plenty down through inland parts of the North Island to the Tararua Range.
"There is also a moderate risk that some of the thunderstorms from the Kaimai Range and ranges of Bay of Plenty and Gisborne down through the central North Island high country to the Tararua Range may become severe producing localised downpours of 25 to 40mm per hour or possibly more and hail of 10 to 20mm diameter."
The weather watchdog recorded 600 lightning strikes yesterday afternoon and evening, the majority over Hawke's Bay.
There were a few instances of lightning between Westport and Greymouth.
Whangārei: Cloudy periods. Chance afternoon shower. Light winds. High 25C Low 15C
Auckland: Cloudy periods. Chance afternoon shower. Sea breezes. High 24C Low 16C
Tauranga: Fine apart from the chance of a morning shower. Northerly breezes. High 22C Low 15C
Whanganui: Morning cloud, then fine spells increasing. A few showers from afternoon. Light winds and sea breezes. High 24C Low 14C
Napier: Cloudy periods. A few showers from afternoon, possibly heavy and thundery with hail. Light winds and sea breezes. High 22C Low 15C
Wellington: Morning cloud, and possible drizzle in the south, then fine spells. A few afternoon showers inland. Southeasterlies. High 21C Low 14C
Christchurch: Often cloudy with occasional rain or drizzle, but some fine breaks developing afternoon. Easterly breezes. High 17C Low 12C
Dunedin: Often cloudy. Occasional drizzle morning and night. Northeast breezes.
High 16C Low 13C