The Snowy Mountains Highway connecting Canberra to the Far South Coast is closed in both directions due to a landslide.
Pictures show two large boulders were dislodged onto the road at Brown Mountain, west of Bemboka.
Live Traffic NSW said heavy machinery would be required to remove the rocks.
"You're best to delay any travel through the area and check Live Traffic for updates," the announcement said.
According to the Bureau of Meteorology, the nearby township of Bemboka has received 2.8mm of rain since 9am on Saturday.
In 2016, one lane of the highway at Brown Mountain due to a landslide.