But MetService is urging residents not to be disheartened yet because it is still early days and the forecast may change.
MetService forecaster Matthew Ford said temperatures in the early part of this week were expected to be near the 20°C mark for most of the southern regions as a ridge of high pressure moves northeast over the country, and culminates in highs of up to 24°C on Wednesday for much of the Otago coastline including Dunedin and Oamaru.
"It looks like there will be westerlies across the lower part of the South Island and there might well be some rain in the west in places like Fiordland and the West Coast, but in the east, you should be nice and sheltered with warm westerly winds."
However, the forecast later in the week looks wetter, he said.
On Thursday, strong northwesterlies were expected in many areas as fronts move on to the South Island from the Tasman Sea, and heavy rain was likely about the Southern Alps and the west of the South Island.
It was likely that warning amounts of rain would fall in Fiordland, the ranges of Westland and the headwaters of the Otago and Canterbury lakes and rivers.
On Friday, fronts were expected to move northwards over the South Island and a low may cross the area later in the day.
It was likely that a heavy rain warning would remain for the ranges of Westland and the headwaters of the Otago and Canterbury lakes and rivers during the morning.
During Labour Weekend (October 26-28), the forecast showed a lot of rain and possible snow at higher altitudes at this stage, so it would be wise for everyone to be prepared and have some indoor activities up their sleeve.
But the forecast was not yet set in stone, Mr Ford said.
"Towards the end of this week, things do look fairly changeable for the lower part of the South Island, so things could change.
"We won’t have a picture locked in until closer to the time.
"Hopefully you’ll be lucky and get some nice weather."
