Thunderstorms are expected to hit the South Island this evening, potentially bringing floods.
A warning is in place tonight for the Canterbury Plains and North Otago, where more than 25mm of rain is expected, along with hail.
MetService has warned people to get prepared for flash flooding around low-lying areas such as streams, rivers or narrow valleys, which may lead to slips.
Driving conditions will also be hazardous, with surface flooding and poor visibility in heavy rain.
Large hail can cause significant damage to crops, orchards, vines, glasshouses and vehicles.
Police have urged holidaymakers returning home to take care on the roads, to drive to the conditions and within speed limits.