Thunderstorm Outlook
Issued at 7:24am 19/08/2026
Valid from 7:24am 19/08/2026 to Midnight 19/08/2026
A strong cold south to southwest flow brings frequent showers to the east coast of the North Island this morning which ease during the day. There is a low risk of a few thunderstorms this morning about coastal areas of Gisborne/Tairawhiti north of Gisborne City as depicted on the chart. Any thunderstorms here are likely to bring strong gusts and small hail. No thunderstorms or significant convection expected elsewhere during this period.
Issued at 8:23am 19/08/2026
Valid from Midnight 19/08/2026 to Midday 20/08/2026
There is minimal risk of thunderstorms or significant convection during this period.
Issued at 8:24am 19/08/2026
Valid from Midday 20/08/2026 to Midnight 20/08/2026
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.
