Issued at 2:46pm 3/09/2026

Valid from 2:46pm 3/09/2026 to Midnight 3/09/2026

Update at 2:45pm to add a moderate risk of thunderstorms for the Southern Alps for this afternoon and evening. A strengthening northwest flow covers the South Island during Thursday, and an active front is forecast to move onto the lower South Island tonight. There is a moderate risk of elevated thunderstorms for the Southern Alps this afternoon and evening and they could bring heavy rain of 10 to 20 mm/h. There is a moderate risk of thunderstorms over Fiordland and southern and central Westland tonight. Thunderstorms here are likely to bring heavy rain of 10 to 25 mm/h, strong wind gusts of 90 to 100 km/h, and possibly a small tornado. A low risk area extends farther east and north, and also covers the likelihood of elevated thunderstorms during the day. There is minimal risk of thunderstorms or significant convection elsewhere during this period.

Issued at 8:46pm 3/09/2026

Valid from Midnight 3/09/2026 to Midday 4/09/2026

Before dawn on Friday, an active front moves across the lower South Island, then farther north during the morning. There is a moderate risk of thunderstorms with this front from Fiordland to northwest Tasman as depicted on the chart, and these thunderstorms could bring heavy rain of 10 to 25 mm/h, strong wind gusts of 90 to 100 km/h, and possibly a small tornado. There is also a low risk of thunderstorms during the morning farther east away from the moderate risk including the Marlborough Sounds, also Kapiti, the Tararua Range and Taranaki as shown on the chart. Then, very cold air aloft moves over the lower South Island during the morning, bringing further instability of the atmosphere. Again, there is a moderate risk of thunderstorms from Stewart Island over Fiordland to southern Westland, accompanied by heavy rain of 10 to 15 mm/h, strong wind gusts of 90 to 100 km/h, and hail of 5 to 15 mm diameter. A larger low risk area extends farther east. No thunderstorms or significant convection expected elsewhere during this period.

Issued at 10:07am 3/09/2026

Valid from Midday 4/09/2026 to Midnight 4/09/2026

During Friday afternoon very cold air aloft moves across the South Island, bringing squally showers. There is a moderate risk of thunderstorms over parts of Westland, Fiordland, southern Southland, Clutha and Dunedin. Any thunderstorms will bring heavy rain of 10 to 15 mm/h, strong wind gusts of 90 to 100 km/h, and hail of 5 to 15 mm diameter. A larger low risk area extends farther east and north. No thunderstorms or significant convection expected elsewhere during this time. During the second half of Friday, very cold air aloft moves across the South Island, bringing frequent showers. From Westland over Fiordland, Southland, Clutha and Dunedin there is a moderate risk during the afternoon, continuing in the evening from Southland to Dunedin. Any thunderstorms here are likely to bring heavy rain of 10 to 15 mm/h, strong wind gusts of 90 to 100 km/h, and hail of 5 to 15 mm diameter. A larger low risk area extends farther north and east. No thunderstorms or significant convection expected elsewhere during this period.