Isolated thunderstorms are expected about inland parts of South Canterbury, North Otago, Dunedin, Central Otago, Clutha and Southland this afternoon and evening (Wednesday).
These thunderstorms will be accompanied by localised heavy rain and hail.
As the thunderstorms will be slow-moving, there is the potential for localised downpours of 25-35mm/hr in some inland places.
Rainfall of this intensity can cause flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.
Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain.
The thunderstorm activity should die away by 9pm this evening.
Note: A Severe Thunderstorm Watch means conditions are favourable for severe thunderstorms in and close to the watch area. People in these areas should be on the lookout for threatening weather conditions and monitor for possible Severe Thunderstorm Warnings.