Severe thunderstorms and hail are forecast for the east of the South Island today.
MetService forecaster Paul Mallinson said strong daytime heat would combine with moisture and wind to raise a moderate risk of severe thunderstorms from northeast Otago to north Canterbury.
The storms are predicted to be very slow-movingwith rainfall of 25-40mm an hour and hail 5-15mm in diameter.
That could lead to flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.