According to the
NOAA forecast, less than an inch of accumulation is possible (50% chance of snow showers) at around 10K, just above the parking lot at Onion Valley. What I would be cautious of more is ice on the switchers of that road. The lower switchbacks are hidden deep in the canyon and tend to hold snow/ice longer.
Slow and easy, but I bet you can make it to the trailhead.