California Mountain Passes

California Department of Transportation publishes it, at Caltrans QuickMap, and that is the page to plan on. California gates are opened and closed by people looking at the road, sometimes several times in a week. What this page holds is the record of how California gates have behaved in past seasons, the measured snowpack at the stations nearest them, and the link and phone number for the agency.

It depends heavily on which road, which is why this page gives a figure per road rather than one for the state. Tioga Road has the deepest record here: across 46 recorded seasons its median closing is November 13, with the earliest on record October 17 in 2004 and the latest January 17 in 2011. That is a spread of 92 days around a median, which is the number that matters: the median tells you when to start paying attention and the spread tells you how little it guarantees.

Carson Pass on SR 88, Echo Summit on US 50, Donner Summit on I-80, Tejon Pass, the Grapevine on I-5, Onyx Summit on SR 38, Cedar Pass on SR 299. These are maintained through the winter and have no seasonal date at all. What varies on them is traction requirements, avalanche control holds and storm closures that last hours rather than months. They are on this page because they are searched for in exactly the same words as the gated ones, and telling the two apart is most of the value of a page like this.

Tioga Road on inside Yosemite, at 9,945 feet. The park half of the Tioga Pass crossing, from Crane Flat to the entrance station at 9,945 feet. The National Park Service closes this gate and Caltrans closes a different one further east, which is why this page keeps two Tioga records.

This page reads it live from the USDA Natural Resources Conservation Service SNOTEL network, which has 5 stations named for and sited at a California pass on this page. Those are physical measurements, a sonic ranger over the snow and a fluid pillow under it, taken at a named station with a stated elevation and a stated date. They are not roadway measurements: a SNOTEL site is an unplowed forest clearing that can sit hundreds of feet above or below the pavement, so read the depth as what the mountain is holding rather than as what the road looks like.

Because no agency publishes one. Angeles Crest Highway is gated for the winter and has no year by year record from any agency: isolated single seasons appear in press releases, and that is all, so there is no median to compute. If Caltrans or a park starts publishing a table, it will appear here.

They are the codes Caltrans itself publishes for each named point on its highways, passed through untouched with the point name, the elevation and the timestamp the agency stamped on them. R-0 means no chain controls are in effect at that point. Every code is checked against the published set before it is shown, because the feed carries the occasional malformed record. The higher restriction levels are shown as codes rather than paraphrased, because the agency’s own wording is what governs whether you may proceed.

Because they are closing two different gates. The National Park Service closes Tioga Road inside Yosemite. Caltrans closes State Route 120 between US 395 and the park boundary, further east and lower down. Across the 7 seasons both agencies have published, the Caltrans gate has gone up later every single time, by between 6 and 56 days, with a median gap of 17 days. The opening dates, by contrast, agree exactly in all 6 overlapping seasons, which is precisely what makes the closing difference easy to miss. This page keeps them as two records with each gate named and never combines them.

California Department of Transportation at Caltrans QuickMap; and National Park Service, Yosemite National Park at the Yosemite current conditions page; and National Park Service, Lassen Volcanic National Park at the Lassen Volcanic conditions page. Caltrans also runs a recorded line on 1-800-427-7623, the Caltrans Highway Information Network, a recorded line that reads out conditions by route number. Every one of those links was checked on 4 September 2026 and returned a working page. They are the source of record for anything happening today.

18: 12 that close behind a gate for the winter and 6 that stay open and are chain or traction controlled instead. 11 of them carry a published year by year record, which is what the tables on this page are built from. The list is the California passes that appear in a machine readable agency feed, have a snowpack station named after them, or carry a published date record, which is the inventory that can be checked against a source.