Thunderstorm Outlook
Issued at 7:44am 17/07/2026
Valid from 7:44am 17/07/2026 to Midnight 17/07/2026
There is minimal risk of thunderstorms or significant convection during this period.
Issued at 9:19am 17/07/2026
Valid from Midnight 17/07/2026 to Midday 18/07/2026
A front approaches the south of the South Island from late morning. There is a low risk of thunderstorms embedded within a rain band for southern Fiordland and Stewart Island as indicated on the chart. Minimal risk of thunderstorms or significant convection for the rest of New Zealand.
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.
