Driving conditions would also be hazardous with surface flooding and poor
visibility in heavy rain.
MetService will continue to monitor the situation closely for severe thunderstorm development and issue further updates.
A severe weather watch is also in place for Fiordland, Dunedin and North Otago.
A front preceded by north-westerly rain is due to move onto the south of the South Island this morning, then moves= slowly northwards over the lower and central South Island during the afternoon and evening.
Meanwhile, a period of southerly rain is forecast for south-eastern parts of the South Island following the passage of the front.