Thunderstorm Outlook
Issued at 7:37am 13/08/2026
Valid from 7:37am 13/08/2026 to Midnight 13/08/2026
A front over Coromandel Peninsula moves into Bay of Plenty this afternoon and becomes slow moving. The air-mass associated with this front is very warm and moist, especially for late winter. There is a low risk of thunderstorms for Coromandel Peninsula this morning, Bay of Plenty west of Opotiki for the whole period, and for Bay of Plenty about and east of Opotiki and northern Gisborne/Tairawhiti from afternoon onwards as indicated on the chart. West of Opotiki, these storms could bring downpours (low risk) of 25-40 mm/h with or without lightning. Elsewhere, there is minimal risk of thunderstorms or significant convection expected during this period.
Issued at 8:32am 13/08/2026
Valid from Midnight 13/08/2026 to Midday 14/08/2026
A front over Bay of Plenty moves slowly eastwards during Friday morning. The air-mass associated with this front is very warm and moist, especially for late winter. There is a low risk of thunderstorms Bay of Plenty and northern Gisborne/Tairawhiti, however west of Opotiki, these storms could bring downpours (low risk) of 25-40 mm/h with or without lightning. A trough affects the Far North of Northland, and there is an associated low risk of thunderstorms from around dawn onwards. Elsewhere, there is minimal risk of thunderstorms or significant convection expected during this period.
Issued at 8:52am 13/08/2026
Valid from Midday 14/08/2026 to Midnight 14/08/2026
A front over eastern Bay of Plenty moves southwards over Gisborne/Tairawhiti during the second half of Friday. There is a low risk of thunderstorms for the very far east of Bay of Plenty and northern Gisborne/Tairawhiti during the afternoon. A trough affecting the Far North of Northland moves away to the north during Friday afternoon, and there is an associated low risk of thunderstorms north of the Bay of Islands as indicated on the chart. Elsewhere, there is minimal risk of thunderstorms or significant convection expected 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.
