James said today was looking like it would be a bit warmer than the average for this time of year.
"There are lots of places looking at lows tonight around 10C in the North Island ... where the average for this time of year is around 3C or 4C.
"So that is quite a bit warmer, but it's going to be not as cold rather than warm."
A front moves on to the South Island from the west this evening, before slowly moving up the West Coast tomorrow.
Heavy rain is expected in Westland south of Otira during this time with MetService predicting about 80 to 110mm to accumulate about the ranges and 50 to 80mm near the coast.
There is a low risk of thunderstorms predicted for Fiordland and Westland tomorrow morning.
Main centre Tuesday forecasts
Whangārei
Morning low cloud or fog then fine, chance afternoon shower. Light winds. High 18C Low 8C
Auckland
Morning low cloud or fog then fine, chance afternoon shower. Light winds. High 17C Low 9C
Hamilton
Morning cloud or fog then fine spells, chance afternoon shower. Northerly breeze.High 17C Low 7C
Tauranga
Periods of rain, possibly heavy, easing this evening. Northeasterlies. High 16C Low 11C
Wellington
Cloudy spells. Chance evening shower. Northerly picking up. High 14C Low 11C
Christchurch
Morning fog or low cloud clearing. High cloud increasing afternoon, and chance shower tonight. Northeasterlies picking up. High 17C Low 7C
Dunedin
Morning fog or low cloud clearing. High cloud increasing from afternoon, chance evening shower. Northeast picking up. High 13C Low 7C
Source: MetService