Seasonal temperatures in the Bay are likely to be above average in May-July.
Niwa's Seasonal Climate Outlook, which was released yesterday, claimed a "mild early winter" was on the cards for much of the East Coast.
Near normal rainfall levels were predicted, as were seasonal soil moisture levels and river flows.
The equatorial Pacific Ocean remained in a neutral state (neither El Nino nor La Nina), while neutral conditions were likely to continue over the next three months.
In the New Zealand region higher pressures than normal are forecast south of the country extending towards the east of the Chatham Islands, while lower pressures than normal are expected to the north of New Zealand.
This pattern is expected to be associated with weaker than normal westerly flow.
Despite temperatures for early winter 2013 predicted to be above average across the entire country, cold snaps along with frosts in some areas were still expected as was typical of early winter.
Sea surface temperatures around New Zealand are forecast to remain above normal over the coming three months.
Rainfall for the May-July period as a whole is likely to be in the near normal range for all regions.