Thunderstorm Outlook
Issued at 8:01am 28/07/2026
Valid from 8:01am 28/07/2026 to Midnight 28/07/2026
There is minimal risk of thunderstorms or significant convection during this period.
Issued at 7:19pm 28/07/2026
Valid from Midnight 28/07/2026 to Midday 29/07/2026
There is minimal risk of thunderstorms or significant convection during this period.
Issued at 9:03am 28/07/2026
Valid from Midday 29/07/2026 to Midnight 29/07/2026
A moist northerly flow develops over the South Island Wednesday afternoon. There is a low risk of thunderstorms with heavy rain for the south of Westland and Fiordland as indicated on the chart. 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.
