Thunderstorm Outlook
Issued at 7:19am 15/07/2026
Valid from 7:19am 15/07/2026 to Midnight 15/07/2026
A west to northwest flow covers much of the country. Within this flow, several fronts are expected to move over the country. Throughout the day, there is a low risk of thunderstorms about the west of the South Island north of the Glaciers, and during the afternoon and evening this risk increases to moderate for western Tasman, Buller, Grey and northern Westland. If these thunderstorms occur they may bring localised heavy rain with intensities of 15 to 25 mm per hour and hail of 5 to 15 mm in diameter. There is also a chance of a coastal tornado. There is also a low risk of thunderstorms this afternoon and evening about the west coast of the North Island from Auckland to Taranaki. Tonight a front moving onto the south of the South Island brings a low risk to southern Fiordland and Stewart Island. Elsewhere, the risk of thunderstorms or severe convection is minimal.
Issued at 10:20am 15/07/2026
Valid from Midnight 15/07/2026 to Midday 16/07/2026
A front moves northwards over central New Zealand during the morning. Another front is slow-moving about Northland. There is a low risk of thunderstorms about Stewart Island and the Clutha District early in the morning and about part of Northland during the whole morning. There is also a pre-dawn low risk of thunderstorms about western Tasman, the Marlborough Sounds and Kapiti and this low risk moves onto Horowhenua, southern Manawatu, coastal Whanganui and Taranaki later in the morning. Elsewhere, the risk of thunderstorms or severe convection is minimal.
Issued at 10:23am 15/07/2026
Valid from Midday 16/07/2026 to Midnight 16/07/2026
A front moves northwards over the North Island. There is a low risk of thunderstorms for northeast Northland during the afternoon, evening and at night. For northern Taranaki and coastal Waitomo there is a low risk of thunderstorms during the afternoon. In the evening and at night there is a low risk of thunderstorms for the west coast of Waikato, Auckland and Northland. Elsewhere, the risk of thunderstorms or severe convection is minimal.
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.
