North Otago residents are being warned to prepare for heavy rain on Tuesday night.
MetService is predicting up to 140mm of rain will fall between midnight Tuesday and noon Wednesday.
The Otago Regional Council says residents north of Dunedin and in low-lying river catchments should expect rivers to rise.
It says the Kakanui, Shag, Taieri and Kyeburn river catchments may be affected and farmers in areas susceptible to flooding should ensure stock are safe.
Meanwhile, South Canterbury has been placed on flood alert for the second time in a week, following a severe weather warning from MetService.
140mm of rain could fall in the foothills in 24 hours from about 9pm on Tuesday. Up to 100mm is predicted for the Canterbury Plains.
The Canterbury Regional Council says the ground throughout the region is still saturated from about 240mm of rain last week.
Farmers are also being told to move stock to higher ground as a precaution.