MetService says a front was forecast to become slow-moving over eastern parts of the South Island from 6pm today until tomorrow, bringing periods of rain, possibly heavy at times.
A severe weather warning has been issued for the ranges of Westland, south of Otira, with 70mm to 100mm of rain expected from 6pm today until 6am tomorrow.
A heavy rain watch is in place for Buller from 9pm today until 6pm tomorrow and a heavy rain warning is in place for the Richmond and Bryant Ranges, the Rai Valley and the Marlborough Sounds until 9pm tomorrow.
Rainfall amounts may approach warning criteria. Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.
Snow may affect passes
A cold front was forecast to move northwards over southern New Zealand on Sunday and central New Zealand on Monday, followed by a change to cooler southerlies.
Although the risk of heavy snow is considered minimal, some of the South Island passes may be affected by snowfall on Sunday and Monday.
