Thunderstorm Outlook
Issued at 8:12am 30/04/2025
Valid from 8:12am 30/04/2025 to Midnight 30/04/2025
The complex trough of low pressure affects northern and central New Zealand, bringing significant weather to many places. There is a moderate risk of thunderstorms this afternoon and evening for southwest Northland, Auckland (including Great Barrier Island), Waikato, Waitomo, the far north of Taranaki, Taumarunui, Taihape, Taupo, Coromandel Peninsula, Bay of Plenty and the far north of Gisborne/Tairawhiti, extending into the night for eastern Bay of Plenty and the far north of Gisborne/Tairawhiti. These thunderstorms may bring localised rainfall rates of 10 to 25 mm/h. A broader low risk of thunderstorms covers remaining North Island regions, excluding southern Wairarapa, Wellington and Horowhenua Kapiti Coast as indicated on the chart. No other areas of thunderstorms or significant convection are expected during this period.
Issued at 7:44pm 30/04/2025
Valid from Midnight 30/04/2025 to Midday 1/05/2025
The complex trough of low pressure moves eastwards across the North Island during Thursday morning, continuing to bring significant weather to many parts of the country. There is a moderate risk of thunderstorms for eastern Bay of Plenty and the far north of Gisborne/Tairawhiti before dawn and during the morning, while for coastal parts of Waikato and Waitomo, there is a moderate risk of thunderstorms before dawn. These thunderstorms may bring localised rainfall rates of 10 to 25 mm/h. There is a broad low risk of thunderstorms covering remaining upper North Island regions from Taumarunui, Taihape and northern Gisborne/Tairawhiti northwards as indicated on the chart. No other areas of thunderstorms or significant convection are expected during this period.
Issued at 9:50am 30/04/2025
Valid from Midday 1/05/2025 to Midnight 1/05/2025
The complex trough of low pressure moves east of the North Island during the second half of Thursday, but continues to bring significant weather to many parts of the country. There is a moderate risk of thunderstorms for far eastern Bay of Plenty and the far north of Gisborne/Tairawhiti this afternoon and may bring localised rainfall rates of 10 to 25 mm/h. There is a surrounding low risk of thunderstorms covering eastern Bay of Plenty, eastern Taupo, northern Hawke's Bay and remaining areas of Gisborne/Tairawhiti during the afternoon as indicated on the chart. No other areas of thunderstorms or significant convection are expected 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.
