Meanwhile, an active front, preceded by strong northwesterlies, is expected to approach the south of the South Island from the Tasman Sea tonight, then move northeast over the South Island tomorrow.
A MetService spokesman said the front was forecast to bring a period of heavy rain to the west coast of the South Island, where a heavy rain warning and watches are in force.
Up to 100mm of rain may accumulate between 6am and 7pm, and peak rates of up to 25mm per hour were expected during that period.
''In addition, a strong wind warning and watches are in force for southern and eastern parts of the South Island.''
An orange warning has been issued for Fiordland between 2am and 4pm; and for Southland, Stewart Island and the Clutha area between 5am and 10pm, he said.
''Northwest gales are forecast to be severe at times, with gusts reaching 120kmh in exposed places.
''Strong wind gusts could damage trees, powerlines and unsecured structures. Driving may be hazardous, especially for high-sided vehicles and motorcycles.''
On the positive side, the temperature is expected to reach 23 deg C in Christchurch tomorrow, and low 20s elsewhere, but is set to drop on Wednesday with highs in the mid-teens.
The spokesman urged residents to keep up to date with the latest forecasts in case any changes are made or further areas added.
