Falling temperatures, heavy rain, gales and large waves are in store as stormy weather heads across much of the country.
MetService is warning thunderstorms are possible in the west of the South Island and parts of Southland and Otago during the day, with north-west gales in central New Zealand pushing temperatures into the mid to high 20s in eastern areas.
Severe gales are forecast to hit the Canterbury high country and Marlborough, except the Kaikōura Coast, and Wellington and southern Wairarapa on Tuesday.
Another burst of heavy rain and thunderstorms likely in southern and western areas on Tuesday.
The weather front is followed by a change to south-westerlies bringing unseasonably cold temperatures to much of the country on Wednesday.
MetService forecaster Peter Little said Dunedin is expected to reach a high of just 17C degrees on Wednesday, while Queenstown's forecast high of 14C on Tuesday and Wednesday is 8.5C below average for this time of year.
That compares to a maximum 28.9 recorded in south Dunedin on Sunday, and 30.5C in Napier - the country's hottest temperature.
"The cool change is also predicted to dump snow on the Southern Alps, with snow forecast to lower to 1000 metres for a time over Fiordland," Little said
Large waves
Strong southwest winds over the Southern Ocean will lead to swells of 6-8 metres on the south and west coasts of both islands from Tuesday to Thursday.
"When these swells are combined with strong southwest winds, waves heights reaching 10 metres are likely about the southwest of the South Island," Little said.
"In addition to the large size of the swell waves, the long period of 16 to 18 seconds between them means the swells will contain a lot of energy and have the potential to cause coastal erosion.
"Anyone planning on being on or near the water in the coming days should be cautious and be sure to check the marine forecast."
Fine weather is due to come back to most places by the end of the week.
On Sunday night, as a first weather front moved in, parts of the country had gales and heavy rain.
MetService said a wind gust of 111 km/h was recorded near Wellington CBD overnight on Sunday.
Some areas of the South Island's West Coast had 100mm of rain in 24 hours.