San Francisco to Lake Tahoe road conditions: I-80 or US-50?

Take I-80 for Truckee and the North Shore, US-50 for South Lake Tahoe. Each crosses a summit above 7,000 feet that goes under chain control in storms, so check the I-80 and US-50 chips above for what is posted right now before you commit.

I-80 or US-50: which route to Tahoe from San Francisco

From San Francisco both routes start the same way, on I-80 across the Bay Bridge and up the valley to Sacramento. US-50 splits off in West Sacramento and climbs past Placerville and over Echo Summit to South Lake Tahoe. I-80 carries on through Auburn and Colfax, over Donner Summit and down to Truckee.

Where you are staying decides it far more than the weather does:

• I-80 for Truckee, Tahoe City, Kings Beach and Incline Village, and for Palisades Tahoe, Northstar, Sugar Bowl and Boreal. From Truckee, SR-89 runs south to Palisades and Tahoe City (SR-89 page) and SR-267 climbs over Brockway Summit to Northstar and Kings Beach (SR-267 page).
• US-50 for South Lake Tahoe, Heavenly and Sierra-at-Tahoe, and for Kirkwood by way of Meyers and Luther Pass.

Getting around the lake to the other side is slow in a storm (SR-89 at Emerald Bay closes when it snows hard), so switching routes to dodge a chain control rarely pays. In dry weather and light traffic the drive is roughly three and a half to four hours either way; Friday-afternoon traffic or a storm can add hours.

Is I-80 or US-50 under chain control right now?

The chips at the top of this page show the worst level on each highway; R-0 means no control is posted. The I-80 page and the US-50 page list every Caltrans checkpoint in driving order with the level at each, refreshed every 3 minutes.

Neither route is reliably better in a storm: Echo Summit is a little higher and steeper, while I-80 carries far more traffic and trucks. If either works for you, take the one that is open and at the lower level; if not, the live list shows how far down the hill the control reaches.

Where chain controls usually start

• I-80: most often eastbound from Kingvale over Donner Summit to the Donner Lake interchange, and westbound from Truckee back to Kingvale. In a bigger storm the eastbound start moves down to Cisco Grove, Alta or Colfax. When Caltrans holds traffic, eastbound drivers wait at Applegate or Colfax and westbound drivers at Truckee. The Donner Pass guide has the full checkpoint list.
• US-50: most often eastbound from Twin Bridges or Strawberry over Echo Summit to Meyers, and westbound from Meyers back to Twin Bridges. Deeper storms push the start down to Riverton, Pollock Pines or Camino, and holds happen at Echo Summit and Meyers. See the Echo Summit guide.
• Around the lake: SR-89 between Truckee and Tahoe City and SR-267 over Brockway Summit get their own controls, often on the same days as I-80.

Chain installers work the busy I-80 checkpoints and the eastbound side of US-50 in storms; they may not sell or rent chains, so bring your own. See how to put on chains.

How long is the drive right now?

On a resort page such as Palisades Tahoe, Northstar or Heavenly, the travel-time card shows the current drive time over the mountain part of the route (from Applegate on I-80, from Placerville on US-50) and says whether traffic is typical or worse than usual. Tap the card's location button for the time from where you are; CHP incidents near the route are listed under it. Highway pages show the alerts but no drive time.

Cameras and message signs worth checking

A camera tells you more than a level: R-1 on wet pavement at Castle Peak is a different drive from R-1 on packed snow.

• On the I-80 route: cameras at Colfax, Whitmore Grade, Soda Springs, Castle Peak and Donner Lake, then Olympic Valley on SR-89 or Brockway Summit on SR-267. Message signs at Gold Run, Baxter, Blue Canyon, Rainbow, Soda Springs and Castle Peak.
• On the US-50 route: cameras at Sly Park, Riverton, Wrights Lake, Twin Bridges and Echo Summit, with Meyers for the drive home. Message signs at Placerville, Sly Park, Ice House Road, Wrights Lake and Twin Bridges.

What today's forecast means for your trip

Under the chain-control headline on each destination page, the Chains outlook row puts the forecast in one sentence: no chain controls expected through a given day, or the window when chains are likely and the level expected. Tap a day chip, or two for a range of up to three days, to see the chance of chains for that trip; "Next 72 hours" opens an hour-by-hour strip. It is a Snowy Roads forecast built from weather data, not a Caltrans announcement, shown only where the forecast covers the route well. The weather card adds expected snow and rain at the resort for today and the next two days, plus any National Weather Service alerts.

If chains look likely during your drive, leave before the storm, go the morning after once plows have caught up, or go prepared. Requirements change without notice, so check again before you leave the Bay Area and once more in Sacramento. Caltrans QuickMap (quickmap.dot.ca.gov) and 1-800-427-7623 are the official sources, and the sign on the road always wins. Whatever you drive, always carry chains.

Get an alert instead of checking repeatedly

Instead of refreshing two highway pages all Friday afternoon, let the iPhone app watch them: tell it what you drive and it says whether you need chains on your route under today's level, then notifies you when a requirement goes up or comes down. Widgets keep your routes on the home screen, with the same cameras, message signs and travel time as the site. It is free and has no ads: see I-80 and US-50 chain control alerts on iPhone.