Thunderstorm Outlook
Issued at 7:57am 23/06/2026
Valid from 7:57am 23/06/2026 to Midnight 23/06/2026
A low is expected to approach the North Island tonight and into Wednesday morning. An associated front, embedded in a northeast flow, is expected to move southwards onto northern parts of Northland tonight with a moderate risk of thunderstorms about northeastern coastal areas between Cape Reinga and Kerikeri, with localised heavy rain of 10 to 25 mm/h possible. In addition, in the evening and at night, there is a low risk of thunderstorms further south and east about Northland as depicted on the chart. In addition, a trough brings a low risk of thunderstorms to southern Fiordland at night. There is minimal risk of thunderstorms or significant convection elsewhere during this period.
Issued at 10:29am 23/06/2026
Valid from Midnight 23/06/2026 to Midday 24/06/2026
A low approaches western parts of the North Island during Wednesday morning, with associated fronts moving onto Northland and Auckland. There is a moderate risk of thunderstorms for northern and eastern Northland before and after dawn, while for the far southeast of Northland, far northern Auckland and Great Barrier Island, the risk of thunderstorms is moderate after dawn. If these thunderstorms occur they will be accompanied by heavy rain of 10 to 25 mm/h. For the southwest of Northland and the majority of Auckland, far northern Waikato and also Coromandel Peninsula, the risk of thunderstorms is low as indicated on the chart. Southern Fiordland is also covered by a low risk of thunderstorms before dawn. In addition, there is a low risk of localised downpours for the northeast of Northland before dawn, which increases to moderate after dawn and spreads into far northern Auckland and Great Barrier Island as indicated on the chart. For the southwest of Northland and the majority of Auckland, the risk of localised downpours remains low. These downpours may occur with or without thunderstorms, and could increased the rainfall rates to 25 to 40 mm/h in localised places. There is minimal risk of thunderstorms or significant convection expected elsewhere 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.
