The winter months of July and August were slightly warmer than average, though we still experienced plenty of the expected frost nights to help reset the vines for spring — a promising start to the season.
However, weather predictability soon went out the window as a rare phenomenon developed: a Sudden Stratospheric Warming (SSW) event over Antarctica in late September 2025. This occurs when an area of relatively warm air forms in the stratosphere above the South Pole — temperatures rising to just below 0°C instead of the usual -55°C. Such events disrupt normal weather patterns, often increasing the likelihood of extreme conditions such as strong winds, heavy rain, and cold outbreaks.
Previous SSW events occurred in the springs of 2002 and 2019, both followed by challenging vintages (2003 and 2020). Those seasons began cool and wet, producing smaller yields but excellent ripening conditions that led to wines of high quality.
The weather we’ve experienced since 21 September has clearly reflected the influence of this SSW. Westerly winds were stronger and more persistent than usual throughout late September and October, and rainfall was more frequent. Fortunately, Grasshopper Rock, situated in the Alexandra Basin, lies further east than most other Central Otago subregions and is naturally sheltered from much of the wind and rain. Both rainfall and wind speeds tend to drop significantly as weather systems move east from the Southern Alps.
Another hallmark of SSW events is the occurrence of short, sharp southerly blasts pushing cold Antarctic air northward. We experienced one such event on 27–28 October, when temperatures remained below 7°C for 24 hours and snow fell to low levels. Frosts that might normally follow did not occur, thanks to the quick return of westerly winds and cloud cover.
As of today (4 November), October temperatures have been below average, and vine growth is approximately a week behind last year. Still, with temperatures peaking at 26°C yesterday, the season remains full of possibilities — and as always, the next two months will tell the real story.