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

R-1: chains or snow tires required. R-2: chains required except 4WD/AWD with snow tires on all four wheels. R-3: chains on all vehicles, no exceptions. This page shows active Caltrans chain controls on the route.

Is US-50 over Echo Summit better?

US-50 is lower (7,382 ft at Echo Summit) but two lanes for much of its length and closes for the same storms. It is an option to South Lake Tahoe, not a reliable bypass to Reno.

I-80 · CA / NV

I-80 over Donner Pass: road conditions right now

Sacramento, CA to Reno, NV

I-80 crosses the Sierra Nevada at Donner Summit, 7,240 feet, between Sacramento and Reno. Sierra storms can drop several feet of snow in a day, and Caltrans chain controls (R-1, R-2, R-3) are the norm from November through April.

Checking the forecast, NWS alerts, and DOT feeds for I-80 right now…

Why this stretch is hard in winter

Chain controls usually start near Kingvale or Colfax on the west side and Truckee on the east.
R-2 means chains on everything except 4WD/AWD with snow tires; R-3 (chains on all vehicles) is rare and often precedes a full closure.
Spinouts on the grade between Colfax and the summit are what actually closes the road most days.
Winter weekends: Reno-bound Friday and Sacramento-bound Sunday traffic backs up for hours at the chain checkpoints.

What this page checks

Hourly forecast at every checkpoint for the time you would be there: temperature, precipitation type and rate, gusts, visibility.
Active National Weather Service watches, warnings, and advisories on the route.
Snow on the ground (NOAA SNODAS) and the Weather Prediction Center winter impact outlook.
Pavement temperature and surface state from state DOT road sensors, when you are leaving within a few hours.
Chain controls, closures, and winter road condition reports from state DOT feeds where they are published openly.
Seasonal closures of mountain roads the router might otherwise use.

Official sources for this corridor

Questions drivers ask about I-80

What do R-1, R-2 and R-3 mean?: R-1: chains or snow tires required. R-2: chains required except 4WD/AWD with snow tires on all four wheels. R-3: chains on all vehicles, no exceptions. This page shows active Caltrans chain controls on the route.
Is US-50 over Echo Summit better?: US-50 is lower (7,382 ft at Echo Summit) but two lanes for much of its length and closes for the same storms. It is an option to South Lake Tahoe, not a reliable bypass to Reno.

Conditions change by the hour. This page is a planning aid built on public forecasts and DOT feeds; the road authority linked above has the final word on closures and chain requirements.

Other corridors: I-80 across Wyoming · I-70 through the Colorado mountains · I-90 over Snoqualmie Pass · I-84 through the Blue Mountains · I-15 over Cajon Pass · I-90 across South Dakota · all corridors