Thunderstorm Outlook
Issued at 8:07am 23/04/2026
Valid from 8:07am 23/04/2026 to Midnight 23/04/2026
An active trough slowly approaches the upper North Island from the east tonight. There is a low risk of thunderstorms for northern parts of Coromandel Peninsula, the Great Barrier Island and the Hauraki Gulf tonight, as well as a low risk of localised downpours with rainfall intensities of 25 to 40 mm/h. There is minimal risk of thunderstorms or significant convection elsewhere.
Issued at 10:36am 23/04/2026
Valid from Midnight 23/04/2026 to Midday 24/04/2026
An active trough lying near Auckland and Great Barrier Island is expected to move slowly north towards Northland during Friday morning. There is a moderate risk of thunderstorms about northern Auckland, Great Barrier Island and for eastern Northland about and south of Bay of Islands throughout the morning which could bring rainfall intensities of 10 to 25 mm/h, as well as a moderate risk of SEVERE thunderstorms with rainfall rates of 25 to 40 mm/h as depicted on the chart. In addition, there is a low risk of thunderstorms and localised downpours (rates of 25 to 40 mm/h) about northern Coromandel before dawn and parts of Auckland and Northland during the morning as indicated on the chart. There is minimal risk of thunderstorms or significant convection elsewhere.
Issued at 10:45am 23/04/2026
Valid from Midday 24/04/2026 to Midnight 24/04/2026
Active trough is forecast to move slowly north over Northland during Friday afternoon and evening. There is a moderate risk of thunderstorms for parts of northern Auckland and Great Barrier Island during the afternoon and for eastern Northland about and south of Bay of Islands throughout the day which could bring rainfall intensities of 10 to 25 mm/h, as well as a moderate risk of SEVERE thunderstorms with rainfall rates of 25 to 40 mm/h as depicted on the chart. This area is also covered by a broadscale heavy rain warning and details can be found here: https://www.metservice.com/warnings/home In addition there is a low risk of thunderstorms and localised downpours (rainfall rates of 25 to 40 mm/h) which extends over remainder of northern Auckland and southern and central Northland as indicated on the chart. There is minimal risk of thunderstorms or significant convection elsewhere.
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.
