A very active front lying over southern Westland this morning was preceded by a strong moist unstable northwesterly flow.

It brought a bout of heavy rain to Fiordland overnight and to the headwaters of the lakes and rivers in Otago. The warning for these areas is now lifted.

Heavy thundery rain is expected to move through Westland this morning to reach Buller early afternoon and the warning is continued for Westland for a further 60 to 80 mm rain with up to 120mm near the divide.

In addition, there will be further significant spill over rain into the headwaters of the lakes and rivers of Canterbury south of the Waimakriri River.

The front should weaken as it moves to the Cook Strait area this evening but a short period (about eight hours) of heavy rain is expected in the Tararua Range as it passes.

The morning rainfall in Westland will be intense for a time. This will lead to rapidly rising rivers and streams.

In the east of the South Island and over Wellington and south Wairarapa, northwest gales were expected in many areas today. Severe gale gusts to 130km/hr in eastern Otago are expected to ease by mid-morning.

In inland parts of Canterbury, severe gale gusts to 140km/hr are possible until about mid afternoon. Further north in eastern Marlborough and about Wellington and southern Wairarapa, northwest gales may gust to 120km/hr through much of the day with gradual easing from the south in all areas by mid evening.

Winds of this strength have the potential to damage trees and powerlines and may make driving hazardous, especially for motorcycles and high-sided vehicles.