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Niwa National Climate Centre meteorologist Ben Noll said there would still be frosts and chills across the southern region, but they were likely to be brief.
In Southland and inland Otago, temperatures are equally likely to be above average or near average; rainfall totals are about equally likely to be near normal or below normal; rainfall deficiencies will continue to be possible in the hydro lake areas; and soil moisture levels and river flows are equally likely to be below normal or near normal.
In coastal Otago areas, temperatures are most likely to be above average; rainfall totals are about equally likely to be below normal or near normal; and soil moisture levels and river flows are most likely to be below normal.
"While rainfall events will occur over the next three months, their frequency may be reduced," he said. "Groundwater and dam level recharge, and increases in river flow and soil moisture, will likely be less pronounced.
"With the end of growing season, there will be less soil water uptake by plants, meaning that soil moisture can recover during rainfall events."
Air pressure was predicted to be higher than normal to the east of the country.
This was expected to be associated with more westerly and northeasterly quarter winds than normal.
During mid and late May, convective forcing was expected to reach the western Pacific with an increasing chance for unsettled weather around New Zealand. In June and July, convective forcing was expected to focus over the eastern Pacific, the Americas and Africa.
"The lack of Madden-Julian Oscillation activity in the western Pacific may result in the continuation of dry spells for New Zealand."