The western and southern parts of the South Island are in for some potentially heavy rain in the coming days, forecasters say.
The rest of the country - particularly the east - is in for some pre-summer sun, however.
"As we head into Wednesday, warm and moist northwesterlies develop over the South Island, bringing rain to western and southern parts of the South Island," MetService meteorologist Dom Barry said on Monday.
"Fiordland has a heavy rain watch in force from Wednesday to Thursday, which is likely to be upgraded to an orange heavy rain warning in the near future."
Christchurch and Oamaru in the south, and Napier/Hastings in the north, will get highs in the mid-20s - the nights not expected to offer much respite, with temperatures likely to drop only a couple of degrees.
The high over the country will move off on Thursday, and while Hawke's Bay will continue to shine for its anniversary day on Friday, the rest of the country should prepare for rain as the long weekend begins.
"Low pressure is returning at the end of this week meaning some wetter weather is in store over the long weekend," Barry said. "With some drier weather possible for Labour Day, it is worth checking the forecast to get the best out of the weekend."
NIWA in September warned of a warmer-than-average spring for eastern parts of the North and South islands.
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