There were seven days when the night temperature dropped to 4C at Whanganui Airport, which brought a risk of frost. Four of those days happened when a slow-moving high pressure system lingered from August 15 to 18.
Kiwifruit orchards had to undertake frost protection at that time. Ohakune had an overnight low of -5.7C on August 15, and it was -6.5C in Turangi.
After a cold start the air warmed on those days of clear skies and light winds. The highest temperatures for the month were on August 20 and 23, with highs of 19 and 20C.
The warmer winter also impacted snow - with less than normal there for skiers on Mount Ruapehu this year. Its ski season ends on October 18 for Tūroa and October 26 for Whakapapa.
The warmer August ends a winter that has been the warmest on record in New Zealand, Niwa says. It was 0.5 to 1.2C warmer than average, especially in the South Island.
Timaru recorded the highest temperature for the month - 25C on August 30.
The average maximum temperature was 12.8C, 2.5C higher than usual.
The reason for this has been warmer sea temperatures - especially warm to the northeast and cooler to the northwest. This has caused more northeast winds, especially for the North Island.
Rainfall was below normal in a lot of places but not north of Auckland, which had been in severe drought during autumn. Kaikohe got 260mm of rain in one day on July 17, a winter one-day record.
Niwa is predicting the northeast winds will continue into spring, with subtropical rain for the north and east of the North Island, and average or below average rain and soil moisture for the Whanganui Region.
Sea and air temperatures will continue to be warmer than average.
Light winds and few showers are predicted today and tomorrow, with a cold front and heavier overnight rain for Thursday.
