Thunderstorm Outlook
Issued at 7:41am 12/10/2026
Valid from 7:41am 12/10/2026 to 1:00am 13/10/2026
There is minimal risk of thunderstorms or significant convection during this period.
Issued at 7:56pm 12/10/2026
Valid from 1:00am 13/10/2026 to 1:00pm 13/10/2026
A front preceded by a moist northwest flow is forecast to approach the far southwest of the South Island late Tuesday morning. There is a low risk of thunderstorms for Fiordland during the morning. There is minimal risk of thunderstorms or significant convection elsewhere during this period.
Issued at 8:21am 12/10/2026
Valid from 1:00pm 13/10/2026 to 1:00am 14/10/2026
The front moves onto the lower South Island during the second half of Tuesday, followed by a narrow ridge. There is a low risk of thunderstorms with and ahead of the front over Fiordland during the afternoon. Meanwhile, for Southland and Otago, there is a low risk of thunderstorms during the afternoon and evening, mostly with the southerly change, as indicated on the chart. There is minimal risk of thunderstorms or significant convection elsewhere 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.
