Both directions of the freeway were closed between Parker and Grapevine roads shortly before 10 a.m.
The CHP office in Fort Tejon made the call to close the interstate when dark clouds over the Grapevine produced snow where it usually doesn't fall.
"We even had reports of snow sticking to the ground on the other side of the Grapevine on the valley floor, near the 5-99 split, which is pretty rare because it's a lot lower elevation," said CHP Officer Eric Priessman.
The roadways reopened around 1 p.m. with police escorting vehicles at slow speeds.
In Ventura, the rain came down at a steady clip - a change of pace for the Ventura High School girls cross country team.
"I wish I had something blocking my face, but it's cold and it's fun, so it's something different," said Melissa Chadwick, a member of the cross country team.
Some of their teammates opted to skip the long distance run in the rain, but the Saturday showers didn't deter other folks from their morning routine.
"We need the rain so bad that this is welcome; it really is," said Michael Voss of Ventura. "If everybody is afraid to go out and get a little cold and a little bit damp, hey you know what? Be brave; suck it up."
The icy conditions were part of a cold front that started moving out of Southern California late Saturday afternoon.