Thunderstorm Outlook
Issued at 7:49am 16/08/2026
Valid from 7:49am 16/08/2026 to Midnight 16/08/2026
A trough moves northwards over northern New Zealand this afternoon and evening as temperatures aloft begin to cool. There is an associated moderate risk of thunderstorms from late afternoon and into the evening in Auckland, Great Barrier Island, northern Coromandel Peninsula, and northern, southern and western areas of Northland. While there is a low risk of thunderstorms about remaining areas of Northland, Coromandel Peninsula, and also in Waikato north of Huntly. These thunderstorms if they occur could bring localised heavy rain with intensities of 10 to 20 mm/h and small hail. Note, over the eastern harbours of Auckland there is the possibility that a funnel cloud or waterspout could be observed. Elsewhere, there is minimal risk of thunderstorms or significant convection during this period.
Issued at 9:06am 16/08/2026
Valid from Midnight 16/08/2026 to Midday 17/08/2026
Before dawn, there is a low risk of thunderstorms about northern and eastern coastal areas of Northland from Bay of Islands northwards, and also about marine areas of eastern Northland further south. No thunderstorms or significant convection expected in other areas of 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.
