Niwa National Climate Centre scientists have forecast unsettled weather with "sharp cold snaps" over the next three months.
DCC infrastructure services general manager Simon Drew said council was closely monitoring coastal erosion in front of Kettle Park and found there had been "moderate erosion" in recent weeks.
He said there was still a "buffer" between the beach and landfill material under Kettle Park, but if the weather caused heavy wave activity in the area, the buffer could be further eroded.
"With a period of unsettled weather looming, around 100 sandbags will be placed along a 50m stretch in front of Moana Rua Rd from tomorrow, to prevent sand washing away from the dune and reduce the erosion of the capping material.
"The bags will likely be in place for a few months.”
Mr Drew asked residents not to climb on the bags or walk in the area above the sandbags because it may affect the integrity of the barrier and the dune.
"It also poses a safety risk to individuals.
"There is still some material from the dunes on the beach, such as concrete, bricks and rubble. This is not content from the landfill."
He said the beach would be closed for a couple of days from the St Clair tennis courts to Moana Rua Rd from tomorrow while contractors fill and place sandbags.
"We’ll continue to monitor the area closely and will re-evaluate and take further action if things change.
“The level of sand on this beach tends to rise and fall throughout the year. There is usually more sand in summer, so levels are likely to rise again in coming months.”
He said council was working with experts to identify the most appropriate way to manage the area from St Clair to St Kilda in the long term.
"We’ll be involving the community in this process from later this year."
