Thunderstorm Outlook
Issued at 7:35am 19/07/2026
Valid from 7:35am 19/07/2026 to Midnight 19/07/2026
A trough affects the Buller and Tasman Districts (and adjacent coastal areas) from afternoon and there is a low risk of thunderstorms as indicated on the chart. Minimal risk of thunderstorms or significant convection for the rest of New Zealand during Sunday.
Issued at 9:07am 19/07/2026
Valid from Midnight 19/07/2026 to Midday 20/07/2026
Strengthening troughs affect parts of the upper North Island during Monday morning. There is a low risk of thunderstorms for coastal Waitomo, coastal Waikato and western areas of Auckland, also northeastern Coromandel and Great Barrier Island, as indicated on the chart. There is minimal risk of thunderstorms or significant convection elsewhere during the first half of Monday.
Issued at 9:13am 19/07/2026
Valid from Midday 20/07/2026 to Midnight 20/07/2026
The low risk of thunderstorms extends northwards and eastwards during the afternoon to cover all of Auckland, also the south of Northland, as indicated on the chart. At this time, the risk of thunderstorms around and over Great Barrier Island increases to moderate. Thunderstorms will generate localised heavy rain with rainfall rates of 10 to 20 mm per hour. There is minimal risk of thunderstorms or significant convection elsewhere during the second half of Monday.
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.
