Claire De Renzy, 3, above, enjoyed a taste of summer at Mission Bay yesterday, but the good weather is expected to turn when a succession of fronts bring heavy rain to western parts of the South Island.
MetService is forecasting the wet weather will reach the North Island by Tuesday, accompanied by strong northwesterly winds.
"So don't put away that extra blanket," Griffiths said.
She said it had been a cool spring to date mainly as a result of the frequent southwesterly winds over New Zealand dragging up cold air from the south.
There had been several cold outbreaks that brought snow and frosts to some regions.
Temperatures had yo-yoed to reach the late-20s in eastern New Zealand before plummeting to near freezing days later.
Griffiths said Auckland had experienced the third-wettest September on record with 175mm of rain, nearly 200 per cent above usual levels. A whopping 266mm of rain fell in the past two months.