Issued at 8:05am 9/05/2025
Valid from 8:05am 9/05/2025 to Midnight 9/05/2025
An active front is expected to cross the northern South Island and the North Island during the day. Several troughs follow the front. There is a generally low risk of thunderstorms and downpours for Westland, Grey, Buller, Tasman and Nelson this morning, spreading to the Marlborough Sounds around midday and Wellington to Whanganui in the afternoon. The risk in these places eases late afternoon or this evening. For the northern half of the North Island there is a low risk of thunderstorms and downpours this afternoon and evening. For Buller and western Tasman, there is a moderate risk of thunderstorms this morning which could bring localised heavy rain with intensities of 10 to 25 mm per hour and a low risk of downpours of 25 to 40 mm per hour. There is a moderate risk of thunderstorms about Northland and Taranaki this morning and afternoon and about Auckland this afternoon. These thunderstorms may bring localised heavy rain with intensities of 10 to 25 mm per hour and a moderate risk of downpours of 25 to 40 mm per hour. There is also a low risk of one or two small tornadoes, especially about the east coast of Northland and near the Hauraki Gulf. For the Coromandel Peninsula and Bay of Plenty there is also a moderate risk of thunderstorms this evening. These thunderstorms may be accompanied by localised heavy rain with intensities of 10 to 25 mm per hour and moderate risk of downpours of 25 to 40 mm per hour. For the areas with a moderate risk of downpours, check the latest Thunderstorm Watch for further details. About Canterbury, there is a low risk of thunderstorms this afternoon bringing localised heavy rain and small hail. No other areas of severe convection or thunderstorms are expected.
Issued at 7:28pm 9/05/2025
Valid from Midnight 9/05/2025 to Midday 10/05/2025
A front near East Cape should move off to the east in the morning. There is a low risk of thunderstorms about eastern Bay of Plenty and northern Gisborne/Tairawhiti before dawn. About the Chatham Islands, there is a moderate risk of thunderstorms during the morning. No other areas of severe convection or thunderstorms are expected.
Issued at 11:34am 9/05/2025
Valid from Midday 10/05/2025 to Midnight 10/05/2025
A front should move onto the south of the South Island during the afternoon and evening. There is a low risk of thunderstorms associated with this front, affecting Stewart Island, the south coast of the South Island and southern Fiordland in the afternoon and northern Fiordland in the evening. No other areas of severe convection or thunderstorms are expected.
In New Zealand, MetService classifies a thunderstorm as severe if one or more of the following criteria are met:
Rainfall of 25mm/h, or more.
Hailstones 20mm in diameter, or larger.
Gusts of 110km/h (60 knots) or stronger.
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.