But Niwa is urging southerners to keep some winter woollies handy, just in case.
National Climate Centre forecasting principal scientist Chris Brandolino said weather conditions continued to shift towards El Nino during August, and the conditions needed to officially classify El Nino in a New Zealand context may be reached this month.
He said temperatures along coastal Otago were equally likely to be near average or above average, and the more frequent westerly winds associated with El Nino may increase the chance for hot days above 25degC, later in the season.
The increased frequency of westerly winds would also likely lead to longer spells of drier-than-normal conditions — particularly from the second half of September.
Soil moisture levels were most likely to be near normal, while river flows were about equally likely to be near normal or below normal.
"Spring may be marked by unusually long dry spells for several regions, owing to a combination of high pressure near the country and lower chances for atmospheric rivers."
On the West Coast, the Southern Alps and foothills, inland Otago, and Southland, temperatures were also equally likely to be near average or above average.
However, rainfall totals were about equally likely to be near normal or above normal, he said.
"Although the first half of September will be drier than normal across much of the region, an increase in moist, westerly winds later in the month may reverse the trend.
"Soil moisture levels and river flows are most likely to be near normal."
While it appeared the southern regions would be warmer than average, he warned the weather could fluctuate wildly during the spring months.
"Spring will come with more southwest winds and occasional outbreaks of cold air as well as episodes of warm-to-hot air from Australia, particularly in eastern areas of both islands."
So hanging up your winter coat for the year is not recommended just yet.
