Highway 38 was closed in both directions near Angelus Oaks on Sunday afternoon and into Tuesday due to mud and flooding, officials said.
Cal Trans have continued to clean up mud and debris on the highway leading up to Big Bear.
Cal Trans said the rain landed in an area of the El Dorado burn scar which made the soil loose when the rain came.
"Last night we had a pretty big monsoon flow come through," Eric Dionne of Cal Trans said. "This is all burn scar from the El Dorado fire so we had contractors in here from that project, they pretty much have this all situated and good to go and then you know how it goes, about a four or five year window of when the slope has no vegetation so the slope is just very easily slideable"
The shutdown spans from Jenks Lake Road to Valley of the Falls Drive, Caltrans announced shortly before 1 p.m. Sunday.
In a tweet, the agency advised drivers to wait until the storm passes or use an alternative route. Cal Trans said it might be until Friday until highway would be reopened.
A flood watch that was issued Sunday morning by the National Weather Service remained in place, affecting the cities of Crestline, Big Bear Lake, Idyllwild-Pine Cove, Big Bear City, Wrightwood, Lucerne Valley, Apple Valley, Lake Arrowhead, Hesperia, Running Springs and Victorville. The flood watch is scheduled to expire at 10 p.m.