Thunderstorm Outlook
Issued at 7:19am 25/07/2026
Valid from 7:19am 25/07/2026 to Midnight 25/07/2026
A front embedded in a strong and unstable southwest flow moves over the North Island today. There is a low risk of thunderstorms for Northland and from Horowhenua to Wellington this morning. Until late afternoon, there is a low risk of thunderstorms for western parts of the North Island from Auckland to Manawatu, also Great Barrier Island, Coromandel Peninsula, parts of Bay of Plenty and the central high country, and coastal Wairarapa, as depicted on the chart. This afternoon and evening there is a low risk of thunderstorms for coastal parts of the Tararua District, Hawke's Bay, and Gisborne/Tairawhiti south of Gisborne City, as drawn on the chart. Elsewhere, there is minimal risk of thunderstorms or significant convection today.
Issued at 7:34pm 25/07/2026
Valid from Midnight 25/07/2026 to Midday 26/07/2026
A shallow low pressure system is forecast to move quickly eastwards over northern New Zealand during Sunday morning, with a trough developing over northern Auckland. There is a low risk of thunderstorms for Northland, Auckland, Great Barrier Island and Coromandel Peninsula north of Tairua. However, from dawn onwards, the risk increases to moderate for Northland and Great Barrier Island, bringing heavy rain of 10 to 25 mm/h, gusts of 80 to 100 km/h, small hail, and the risk of a small tornado (mainly near the coast). There is minimal risk of thunderstorms or significant convection elsewhere in New Zealand during Sunday morning.
Issued at 9:05am 25/07/2026
Valid from Midday 26/07/2026 to Midnight 26/07/2026
A second trough, which is followed by a change from westerly to southerly winds, is forecast to move northeastwards over Northland during Sunday afternoon. This trough is accompanied by cold temperatures at upper levels, making the atmosphere unstable. During the afternoon there is a moderate risk of thunderstorms for Northland, and a low risk for Great Barrier Island and Auckland north of Whangaparaoa. Any thunderstorms that occur will likely be accompanied by heavy rain with rates of 5 to 15 mm/h, and small hail. There is minimal risk of thunderstorms or significant convection elsewhere in 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.
