A state of emergency was declared on Thursday due to concerns of rapid erosion from the sea and Waiau River during a king tide over the weekend.
Eighteen properties are affected, although only six are permanent residences.
There was also an old community tip that may also contain possible explosives that was exposed to the erosion.
The community lost about three metres of land in a day last week as the river ate into gravel, sand and bank.
An attempt would be made to open the Waiau River mouth to the sea to direct flow away from the properties this week.
Southland District Mayor Rob Scott signed off the extension at 8.40am this morning after Emergency Management Southland controller Simon Mapp recommended the extension continue.
Mr Mapp said work as continuing on opening the cut in the Waiau River mouth and he hoped it would be complete by next week.
The Bluecliffs community was still at risk and a specialist was onsite today to investigate options to clear the tip site.
It was hoped the bar opening would reduce erosion in front of the property and tip for a period of time buying time to continue conversations with the community about the future of the area.
The timing of sea swells and tides would play a key part in the success of the opening.
Meridian Energy was supporting the process by influencing the river flow.
"It is a highly complex and changing environment, and it’s unknown how well this opening may work or how much time this might provide the residents," Mr Mapp said.
This week, Emergency Management Southland would restrict public access to the boat ramp and some roads in the area to manage access to the active work site for contractors.
After reports of people visiting the area to have a look, Mr Mapp urged the public to avoid any unnecessary travel to the area during the state of emergency.
