Donner Summit Road Conditions

Live Caltrans chain controls and closures for I-80 over Donner Summit and the Tahoe highways, with a plain guide to what the numbers mean.

This panel reads Caltrans chain-control and closure data for I-80, Hwy 89, Hwy 267 and Hwy 28 and refreshes every five minutes. For the official word before you drive, use Caltrans QuickMap or call 1-800-427-7623. This page never says a road is safe; it shows what Caltrans has posted.

Chain control levels

Level	What it means
R-1	Chains or snow tires required on the drive axle.
R-2	Chains required on all vehicles except four wheel drive with snow tires on all four wheels.
R-3	Chains required on all vehicles, no exceptions.
Closed	No travel until Caltrans reopens the road.

Truckee to the summit: the temperature gap

Truckee sits at about 5,817 feet. I-80 tops out at Donner Summit near 7,239 feet. That is roughly 1,400 feet of climbing in about 15 miles. Free air cools about 3.5 degrees Fahrenheit for every 1,000 feet, so the summit usually runs around 5 degrees colder than town, and it often gets more snow. The worst days are when the snow level sits between the two: Truckee gets rain, the summit gets snow, and the road in between ices up.

Road surface can freeze even when the air reads a few degrees above 32. Bridges, shaded corners and the Truckee River canyon freeze first. When the forecast shows a freeze overnight, assume black ice on the morning drive.

Before you go

• Check the 22 live Caltrans highway cameras on the Truckee weather page for what the road looks like right now.
• See what is coming on the Kerr Storm Tracker, errolkerr.com's own future radar built from NEXRAD, HRRR and GFS with a self-grading accuracy loop.
• Read the Truckee weather forecast and the published forecast accuracy against the Truckee airport station.
• Carry chains that fit your tires, a shovel, water, a blanket and a full tank. Fuel up in Truckee before the climb.

Questions

Is I-80 over Donner Summit open right now?

The live panel above shows what Caltrans has posted and updates every five minutes. For the official status use quickmap.dot.ca.gov or 1-800-427-7623.

What do R-1, R-2 and R-3 mean?

R-1 is chains or snow tires on the drive axle. R-2 is chains on everything except four wheel drive with snow tires on all four wheels. R-3 is chains on every vehicle.

How much colder is Donner Summit than Truckee?

About 5 degrees on average from the roughly 1,400 foot elevation gap, with more snow, and the gap matters most when the snow level is between the two.

Who runs this page?

Errol Kerr, a Truckee excavation foreman at Ruppert Inc. and owner of E Kerr LLC (equipment rental), built it for the crews and neighbors who drive the corridor. See about Errol Kerr.