Live answer for the drive to Mammoth Mountain and June Mountain: US-395, SR-203 into Mammoth Lakes and SR-158 to June Lake, from Caltrans and refreshed every few minutes.
Yes, chain controls are up: R-1 on SR-203 at Mammoth Lakes; R-1 on US-395 at Mammoth Lakes, June Lake, Lee Vining and Bridgeport (chains required except vehicles with snow tires). As of 11:08 pm Pacific.
Live roads, cams and lots
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Before you go
US-395 north of Bishop and SR-203 into town are where chain controls usually go up. Mammoth gets big storms, so carry chains that fit your tires even with 4WD. Mammoth and Highway 395 cams and conditions.
What the levels mean: R-1 means chains are required unless you have snow tires; R-2 means chains are required on everything except 4WD/AWD vehicles with snow tires on all four wheels (and those must still carry chains); R-3 means chains on all vehicles, no exceptions. Full R-1, R-2, R-3 explainer · How to put on chains.
Lots, cams and crowd calendar by resort: Mammoth Mountain · June Mountain.