Thunderstorm Outlook
Issued at 7:07am 18/06/2026
Valid from 7:07am 18/06/2026 to Midnight 18/06/2026
There is minimal risk of thunderstorms or significant convection during this period.
Issued at 8:12am 18/06/2026
Valid from Midnight 18/06/2026 to Midday 19/06/2026
There is minimal risk of thunderstorms or significant convection during this period.
Issued at 8:35am 18/06/2026
Valid from Midday 19/06/2026 to Midnight 19/06/2026
A northwesterly flow covers the South Island during the second half of Friday with embedded fronts bringing rain to Westland and Fiordland. There is a low risk of thunderstorms with heavy rain about the fiords of central and southern Fiordland from mid afternoon, and about other parts of Fiordland, the ranges of southern Westland, coastal Southland and Stewart Island at night. There is a minimal risk of thunderstorms or significant convection of other parts of New Zealand on Friday.
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.
