Severe gales powerful enough to damage trees and power lines are set to lash the east coast of the South Island and the parts of the North Island.

MetService has issued a weather warning for the lower South Island as winds threaten to hit 100km/h in an early winter storm.

A severe weather warning has been issued for the South Island after gales battered Wellington today.

North Islanders stifled by the heat should sleep easier from tomorrow - tonight should be the last in a run of extremely stuffy nights.

Muggy nights of up to 100 per cent humidity have swamped the north of NZ since the weekend and look set to continue for a couple more days.

An anticyclone moving slowly over NZ is likely to bring the hottest days of summer yet, MetService spokesman Bob McDavitt says.

Rain eased in Gisborne overnight and surrounding roads reopened after flooding and slips caused evacuations.

MetService forecaster Peter Smith said the weather should mimic the pattern of the past week and would be good for those heading to the beach.

Residents living south of Auckland are being warned to brace themselves for a stormy night.

Heavy rain and possibly even thunderstorms are forecast for southern parts of Auckland today.

Unsettled conditions could mark a turning point for our summer weather, forecasters say.

Simon Power confirms the MetService is negotiating with the BBC to provide some forecasting services.

A short-sharp barrage of rain and hail pummelled Invercargill today leaving the city looking like a scene from mid-winter.

A vigorous front which has hammered the lower South Island with high winds and rain will attack central parts of the country today.