Issued at 7:53am 31/08/2026

Valid from 7:53am 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 southern parts from southern Fiordland and Southland, also Clutha, Stewart Island and much of Dunedin this morning and 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, which also includes North Otago. In addition, there is a low risk extending northward over the Canterbury Plains and North Canterbury this afternoon (including Banks Peninsula), which extends up to the southeastern parts of Wairarapa, including the southern tip of the Remutaka Range this evening. 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.

Issued at 6:59pm 31/08/2026

Valid from Midnight 31/08/2026 to Midday 1/09/2026

A strong, cold and unstable southwesterly flow covering much of the country eases during the morning. There is a low risk of one or two thunderstorms about the Clutha coast, including the Catlins, before dawn. Although not depicted on this chart, there is a moderate risk of thunderstorms for the Chatham Islands, bringing gusts of around 100 km/h and small hail.

Issued at 9:23am 31/08/2026

Valid from Midday 1/09/2026 to Midnight 1/09/2026

There is minimal risk of thunderstorms or significant convection during this period. Although not depicted on this chart, there is a moderate risk for the Chatham Islands, bringing gusts of 90 to 100km/h and small hail until mid-evening.