Thunderstorm Outlook
Issued at 7:24am 9/10/2026
Valid from 7:24am 9/10/2026 to 1:00am 10/10/2026
There is minimal risk of thunderstorms or significant convection during this period.
Issued at 8:52am 9/10/2026
Valid from 1:00am 10/10/2026 to 1:00pm 10/10/2026
There is minimal risk of thunderstorms or significant convection during this period.
Issued at 8:54am 9/10/2026
Valid from 1:00pm 10/10/2026 to 1:00am 11/10/2026
A broad trough moves slowly east onto New Zealand bringing periods of rain and showers to many areas. There is a moderate risk of thunderstorms in the afternoon and evening for inland Canterbury, the far north of the Lakes District, inland Westland, Grey and Buller and about the Nelson Lakes. These storms may be accompanied by heavy rain, 10 to 15 mm/h and small hail. There is a low risk of thunderstorms in the afternoon and evening affecting much of the remainder of the South Island as indicated on the chart. In the evening and at night there is a low risk of thunderstorms of the north and east of Northland as indicated on the chart. These storms may be accompanied by heavy rain, 10 to 15 mm/h. There is minimal risk of thunderstorms or significant convection elsewhere in New Zealand 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.
