California Chain Control Today: Live Caltrans Status for Every Ski Route

Live data from the Caltrans chain control feed, read in your browser when the page loads. Caltrans publishes it about once a minute; each panel shows the time Caltrans published the data it is showing.

Before any mountain drive: check the panel for your route, then confirm on Caltrans QuickMap or by calling 1-800-427-7623. Conditions change within minutes, and every vehicle entering a chain control area must carry chains or traction devices, even if it is exempt from fitting them. New to this? Read California chain control, explained.

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I-80 over Donner Summit

Checking Caltrans…

For Sugar Bowl, Boreal, Palisades Tahoe, Northstar and the other North Lake Tahoe resorts, and the usual Bay Area route to Mammoth. I-80 guide

US-50 over Echo Summit

Checking Caltrans…

For Heavenly, Sierra-at-Tahoe and South Lake Tahoe lodging. US-50 guide

SR-88 over Carson Pass

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For Kirkwood. Also closes for avalanche control during and after storms. SR-88 guide

US-395 and SR-203 to Mammoth

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For Mammoth Mountain and June Mountain. US-395 guide

SR-18, SR-330 and SR-38 to Big Bear

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For Snow Summit, Bear Mountain and Snow Valley. Big Bear guide

How to read these panels

Each panel summarises the strictest passenger car restriction Caltrans is reporting anywhere on that route, and names where it is in effect. Green means Caltrans reports no chain controls on that stretch right now. Amber means R1 or R2. Red means R3 or a closure.

The panels are built to fail safe. If Caltrans cannot be reached, if its data is more than ten minutes old, if part of a route is not reporting, or if Caltrans returns a status the panel does not recognise, it shows no status at all and sends you to QuickMap. It never shows a bare all clear.

Each route only counts the reporting points that matter for a ski trip: I-80 above 4,500 feet, US-50 above 4,900 feet, SR-88 above 7,000 feet, US-395 and SR-203 inside Mono County on the Mammoth stretch, and SR-18, SR-330 and SR-38 above 4,000 feet in San Bernardino County. A control far down the hill does not turn a panel amber.

Routes not on this page

Several resorts depend on smaller roads with their own controls: Northstar on SR-267 over Brockway Summit, Homewood and Granlibakken on SR-89 along the west shore, Bear Valley on SR-4, Dodge Ridge on SR-108, China Peak on SR-168, and Mountain High on SR-2 and SR-138. Check those on QuickMap. SR-4 is left off deliberately: Caltrans closes it for the winter at Ebbetts Pass, beyond Bear Valley, and a route summary would show that closure as if it applied to the resort.

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Chain control today: frequently asked questions

Is chain control in effect in California right now?

The panels at the top of this page read the Caltrans chain control feed for the five main ski routes each time you load the page, and show the time Caltrans published the data. If a panel cannot reach Caltrans or the data is more than ten minutes old, it says so instead of showing a status. Always confirm on Caltrans QuickMap or by calling 1-800-427-7623 before you drive.

What is chain control?

Chain control is a temporary restriction Caltrans posts on a stretch of mountain highway during winter weather. While it is in effect, vehicles must have tire chains or approved traction devices fitted to continue, unless they meet the exemption for the level posted (R1, R2 or R3), and every vehicle entering a chain control area must carry traction devices.

What do R1, R2 and R3 mean?

R1 requires chains except on passenger vehicles and light trucks under 6,000 pounds with snow tires on at least two drive wheels. R2 requires chains or traction devices except on four wheel and all wheel drive vehicles with snow tread tires on all four wheels. R3 requires chains or traction devices on all vehicles, with no exceptions.

How often does this page update?

Caltrans publishes its chain control feed about once a minute. This page fetches it when you load the page and reuses the result for up to a minute after that, so reload for the latest status.

Why does a route say live status unavailable?

The panel could not reach the Caltrans feed, the data was more than ten minutes old, or Caltrans reported a status for part of the route that the panel does not recognise. Rather than guess, it shows no status and points you to Caltrans QuickMap. That is deliberate: a wrong all clear is worse than no answer.

Related guides

Live chain control data comes from the Caltrans Commercial Wholesale Web Portal, which Caltrans publishes about once a minute. SnoCal is not affiliated with Caltrans and the data is provided without warranty. Always confirm conditions with Caltrans before you travel.