Metservice has issued a Severe Weather Watch for Buller and Northwest Nelson, predicting heavy rain for central and northern New Zealand.
The heavy north to northwesterly rain is a result of a slow-moving front currently positioned over the upper South Island, which will be followed by a colder southerly flow.
The watch has been issued with the possibility that rainfall amounts will reach warning criteria in northwest Nelson on Saturday afternoon and evening.
The ranges of Buller are experiencing heavy rain easing this afternoon, but another period of heavy rain is forecast for Saturday afternoon and evening.
Forecasters are monitoring the situation and updates will be posted on Nelson Live should the Watch be replaced by a Warning.