Heavy rain and strong winds and yesterday's king tides meant residents should be aware of an increased risk of flooding and take steps to maintain the safety of themselves and their property, Grafton said.
"Get as much of your home contents out of harm's way as possible, secure heavy outdoor objects and park vehicles in garages if you can.
"If you have electronics you can't move in low-lying areas, switch them off at the wall.
Make sure you can access emergency equipment like torches and portable radios at all times."
States of emergency have been declared in Buller and Dunedin, and evacuations have been triggered in Westport, Mapua and the Nelson-Tasman region.
Residents in all parts of the South Island have been cautioned to stay inside and away from beaches and exposed areas.
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Flood recovery tips:
• Do not do anything that puts your safety at risk or causes more damage to your property.
• Contact your insurer, or insurance adviser, as soon as possible.
• Avoid entering flood water, either on foot or in a vehicle. Flood water can contain raw sewage and contaminants, conduct electricity and mask hidden hazards, and poses a serious hazard to health. It may be deeper, or moving faster, than you expect.
• Try to make buildings safe and weatherproof but don't make any emergency repairs unless it is safe to do so. Don't start non-essential repairs without your insurance company's approval.
• If water has entered your property, don't turn on your electricity until it has been inspected by an electrician.
• Get essential services, such as water, electricity, gas and sewerage, repaired and keep copies of any invoices.
• Do what's necessary to make your home safe and sanitary. When cleaning, wear a mask, gloves and overalls to minimise exposure to possibly-hazardous materials.
• Take pictures and make a list of any perishables you have to dispose of.
• Remove and discard any water or mud-damaged goods that pose a health risk, such as saturated carpets and soft furnishings.
• Take photos of damaged property to help speed up the assessments and claims process.
• Keep any damaged items that don't pose a health and safety risk.
• Do not drive your vehicle if it has suffered water damage.