Thunderstorm Outlook
Issued at 7:14am 10/08/2026
Valid from 7:14am 10/08/2026 to Midnight 10/08/2026
A low lies slow-moving today just east of the South Island, while cold air aloft over central New Zealand moves away to the east. There is a low risk of thunderstorms until mid-morning from South Taranaki to Kapiti, extending into the Tararua Range. Not shown on the chart, there is also a low risk of thunderstorms about the Chatham Islands, both this morning and again late afternoon and evening. Elsewhere over New Zealand, there is minimal risk of thunderstorms or significant convection during this period.
Issued at 8:30am 10/08/2026
Valid from Midnight 10/08/2026 to Midday 11/08/2026
There is minimal risk of thunderstorms or significant convection during this period.
Severe Thunderstorm Criteria
In New Zealand, MetService classifies a thunderstorm as severe if one or more of the following criteria are met:
Heavy rain (from thunderstorms):
Rainfall of 25mm/h, or more.
Large hail:
Hailstones 20mm in diameter, or larger.
Strong wind gusts (from thunderstorms):
Gusts of 110km/h (60 knots) or stronger.
Damaging tornadoes:
Fujita F1 - i.e. wind speeds greater than 116km/h (63 knots) or stronger.
Note: some tornadic systems such as funnel clouds, waterspouts and small land-based tornadoes are possible with thunderstorms that may not be classified as severe.
