Issued at 4:40pm 30/08/2026

Valid from 4:40pm 30/08/2026 to Midnight 30/08/2026

A strong cold and unstable southwest flow affects the south and east of the South Island. There is a low risk of squally thunderstorms throughout the period about Fiordland, and also for Banks Peninsula this afternoon. However, the risk is considered moderate for Southland, Clutha, Dunedin and North Otago, where thunderstorms may be accompanied by wind gusts of 80 to 100 km/h and small hail. There is minimal risk of thunderstorms or significant convection elsewhere in New Zealand during this period.

Issued at 8:17pm 30/08/2026

Valid from Midnight 30/08/2026 to Midday 31/08/2026

A strong cold and unstable southwest flow affects much of the South Island. There is a low risk of thunderstorms about parts of Fiordland, Southland through into North Otago, which rises to moderate about the southeastern corner from Stewart Island, southeast Southland, Clutha and much of Dunedin during the morning as indicated on the chart. These thunderstorms bring heavy rain of 10 to 15 mm/h, gusts of 90 to 110km/h and small hail. Also, during the morning, the low risk extends north to include Banks Peninsula as depicted on the chart. Although not indicated on the chart, there is a moderate risk of thunderstorms about the Chatham Islands after dawn, with gusts of 80 to 100km/h and small hail. There is minimal risk of thunderstorms or significant convection elsewhere in New Zealand during this period.

Issued at 10:17am 30/08/2026

Valid from Midday 31/08/2026 to Midnight 31/08/2026

A strong cold and unstable southwest flow covering the much of the South Island is expected to slowly spread north over the lower North Island later in the day. There is a moderate risk of thunderstorms about the southeastern corner from Stewart Island to Otago Peninsula (including coastal parts of Clutha) during the afternoon, bringing heavy rain of 10 to 15 mm/h, gusts of 90 to 110km/h and small hail. There remains a broader low risk throughout the period extending further inland as depicted on the chart. In addition, there is a low risk extending northward over Banks Peninsula, including the southeastern coast of Wairarapa. Although not indicated on the chart, there is a moderate risk of thunderstorms about the Chatham Islands, bringing gusts of 80 to 100km/h and small hail. There is minimal risk of thunderstorms or significant convection elsewhere in New Zealand during this period.