During Wednesday afternoon and early evening, daytime heating and wind convergence are likely to produce isolated showers over parts of both islands. Over eastern Northland, and inland South Island from Tasman/Nelson to eastern Otago, there is a low risk of a few thunderstorms in the afternoon and evening. No thunderstorms or significant convection expected elsewhere during this period.

During the first half of Thursday, an active front briefly brings heavy rain to Fiordland and southern Westland. There is a general low risk of thunderstorms, but with the passage of the front the risk briefly rises to moderate, with rainfall intensities of 10 to 25mm/h. No thunderstorms or significant convection expected elsewhere during this period.

Through the second half of Thursday, the front continues to sweep up the west coast of the South Island, and there is briefly a moderate risk of thunderstorms with heavy rain of 10 to 20 mm/h. In the east of the South Island, cold air aloft should boost instability, and there is a moderate risk of thunderstorms about the North Otago and South Canterbury, with a larger low risk area extending farther north and south. Rainfall intensities here could reach 10 to 25 mm/h, and there is a risk of small hail. Farther north, there is a low risk of thunderstorms about Kaikoura Ranges. Over the North Island, daytime heating and wind convergence will produce showers over inland Bay of Plenty and Gisborne-Tairawhiti, and there is a low risk of thunderstorms. No thunderstorms or significant convection expected elsewhere during this period.