Drivers were not allowed to drive up to the summit because of the slick road conditions, so some people parked their vehicles a mile below.
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Park rangers said it snowed overnight and it had been hailing throughout the day Sunday off and on.
Some people decided to have some fun by sledding, while others enjoyed a nice walk through the snow.
The Mount Diablo State Park is officially closed at this time.
Other parts of the Bay Area also got a dusting of snow.
Watch the video player above for Lilian Kim's full report.
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