MetService meteorologist Joshua Griffin said overnight lows should recover from a cold snap that arrived on Thursday last week.
However, weather models were "a little bit fiddly" and the picture for the coming weekend remained uncertain yesterday.
A high had settled over the lower half of the country resulting in clear skies and very light winds that allowed the ground’s heat to radiate out and drop temperatures "quite low".
In Christchurch, the cold spell culminated in residents waking to a low of -5°C on Sunday morning.
In Oamaru, last week’s cold spell started at -0.5°C and dipped to -1.1°C on Saturday.
In Dunedin, temperatures dropped to 2°C on Thursday and then reached a 0.9°C overnight low on Saturday.
From last night onwards temperatures appeared to be returning to normal for this time of year — "not as cold as we were seeing previously".
Christchurch is expecting a low of 1°C tomorrow, and then 7°C on Wednesday. Queenstown was expected to recover to -1°C tomorrow and then a low of 2°C on Wednesday.
Dunedin lows were expected to rise to 3°C or 5°C.
"There’s a little bit of a weak feature approaching the South Island", Mr Griffin said.
"Associated with that, it’s going to have a little bit more cloud cover, which is going to help keep some of the heat trapped overnight.
"We’re also going to have a little bit of a northwesterly wind picking up.
"With those winds blowing it doesn’t allow the ground to cool as much as whenever there’s no wind."
It would be fine across much of Canterbury sand Otago.
Tomorrow, wind would strengthen somewhat over the lower parts of the South Island.
Then on Wednesday, northwesterly winds would again strengthen ahead of an incoming front — western parts of Southland could experience some windy conditions.
The front moving over on Wednesday could bring rain to the deep south, Mr Griffin said.
"Beyond that, towards Thursday and Friday, the models really diverge quite a bit, so there’s quite a bit of uncertainty in the forecast there."
