Thunderstorm Outlook
Issued at 7:26am 2/04/2025
Valid from 7:26am 2/04/2025 to 1:00am 3/04/2025
A front approaches New Zealand during the latter half of Wednesday, bringing rain to western areas of the South Island. There is an associated low risk of isolated thunderstorms embedded in bands of rain offshore Westland and northern Fiordland, as indicated on the chart. No thunderstorms or significant convection expected elsewhere.
Issued at 8:05pm 2/04/2025
Valid from 1:00am 3/04/2025 to 1:00pm 3/04/2025
Fronts bring significant rain to parts of the South Island. Please refer to the Severe Weather Warnings and Watches which are in force. There is a low risk of isolated thunderstorms embedded within the rain for western parts of the South Island, as indicated on the chart. However, the risk is considered moderate for Westland south of about Hokitika, and northern Fiordland. Thunderstorms will enhance local rainfall rates, up to 30 mm per hour. No thunderstorms or significant convection expected elsewhere during the first half of Thursday.
Issued at 10:18am 2/04/2025
Valid from 1:00pm 3/04/2025 to 1:00am 4/04/2025
Fronts bring significant rain to parts of the South Island. Please refer to the Severe Weather Warnings and Watches which are in force. There is a low risk of isolated thunderstorms embedded in the rain, as indicated on the chart. However, the risk is considered moderate for Westland south of Abut Head, and northern Fiordland. Thunderstorms will enhance local rainfall rates, up to 25 mm per hour. No thunderstorms or significant convection expected elsewhere during the second half of Thursday.
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.
