Civil defence officials are on alert, with heavy rain, snow and flooding in many South Island areas

Severe weather warnings are in effect for much of Otago, Canterbury and Tasman District.

South Island passes have reopened after earlier snowfall, but State Highway One at Seddon in Marlborough is likely to stay closed all day because of flooding.

Motorists in Christchurch, Ashburton and Timaru are also being warned to take care in flooded areas.

People are being urged to avoid rapidly rising rivers and streams across Otago.

In the North Island, parts of Coromandel Peninsula are cut off by flooding and slips, and some local Northland roads still have flooding issues.