Thunderstorm Outlook
Issued at 7:39am 27/09/2026
Valid from 7:39am 27/09/2026 to 1:00am 28/09/2026
A fast moving front sweeps northeast across New Zealand today, followed by a showery southwesterly flow. For the far south of Westland, Fiordland, coastal Southland, coastal Clutha and Dunedin there is a low risk of thunderstorms this morning with small hail. For the remainder of Westland and Buller there is a low risk of thunderstorms with small hail this morning and afternoon. For the Marlborough Sounds, Wellington and Wairarapa there is a low risk of thunderstorms this afternoon and into the evening, especially associated with a southerly change early afternoon and following the change. Elsewhere, there is minimal risk of thunderstorms or significant convection.
Issued at 8:51am 27/09/2026
Valid from 1:00am 28/09/2026 to 1:00pm 28/09/2026
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.
