Thunderstorm Outlook
Issued at 7:16am 22/07/2026
Valid from 7:16am 22/07/2026 to Midnight 22/07/2026
There is minimal risk of thunderstorms or significant convection during this period.
Issued at 7:05pm 22/07/2026
Valid from Midnight 22/07/2026 to Midday 23/07/2026
A front moves onto the lower South Island during Thursday morning. There is a low risk of thunderstorms over Fiordland and Stewart Island, especially during the latter part of the morning. Elsewhere over New Zealand, there is minimal risk of thunderstorms or significant convection during this period.
Issued at 7:16pm 22/07/2026
Valid from Midday 23/07/2026 to Midnight 23/07/2026
During Thursday afternoon and evening, the front moves northwards across Westland, followed by a second front over Fiordland, this one accompanied by colder air aloft. There is a moderate risk of thunderstorms over Westland, with heavy rain of 10 to 25 mm/h and strong wind gusts of 90 km/h. Over Fiordland and parts of Stewart Island, there is a moderate risk of thunderstorms, both with the first front which could bring heavy rain of 10 to 25 mm/h and strong wind gusts of 90 km/h, and with the second front which is likely to be accompanied by small hail, but less intense rain and winds. A broader low risk extends farther north and east. Elsewhere over New Zealand, there is minimal risk of thunderstorms or severe 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.
