A front over southern New Zealand is sweeping northward today bringing rain to most regions.
On Tuesday night the front was moving slowly northwards and would pass over the remainder of the South Island this morning.
The front is preceded by a strong, moist, northerly flow and is followed by unsettled westerlies.
"This front is expected to deliver a period of heavy rain and northerly gales, especially to central and southern parts of New Zealand," MetService said.
A heavy rain warning was in place for Westland, south of Otira until 11am today.
"Heavy rain is expected to ease gradually from the south by late Wednesday morning. Until this time expect 70 to 110mm to accumulate about the ranges, and 40 to 70mm near the coast.
"Peak intensities of 15 to 25mm per hour during Wednesday morning," MetService said.
MetService national forecast
Whangārei - Cloudy with a chance of showers, then rain from the evening, easing overnight as northerly turns westerly. High 17C Low 9C
Auckland - Cloudy with a shower or two, then rain from the evening, easing overnight as northerly turns westerly. High 16C Low 10C
Tauranga - Some rain at times, persistent in the evening. Northerlies. High 16C Low 8C
Napier - High cloud, then rain from evening. Northerlies. High 16C Low 6C
New Plymouth - Few morning showers then rain, possibly heavy evening with strong northerly. Rain and wind easing at night. High 14C Low 9C
Wellington - A few showers, then rain from the evening. Northerlies rising to gale in exposed places and gusting 90 km/h. High 13C Low 9C
Christchurch - Mostly cloudy. Occasional rain developing this morning then clearing evening as gusty northeasterlies turn southwest. High 14C Low 3C
Greymouth - Rain, heavy falls, turning to showers afternoon as strong northerlies turn westerly. Possible thunderstorms and hail. High 13C Low 5C
Invercargill - Cloudy periods clearing by evening. Northerly breezes. High 13C Low 1C