Road Closures
Caltrans Road Conditions
This information is very accurate and updated often. If you know the highway you're looking for (120, 108, 88, etc) enter it on the road information page. From webcams to closures to traffic, there's a lot of information available at the Caltrans Quickmap - under 'options' webcams, and message signs are often very useful, as well as all of the road conditions.
Yosemite
Longer term conditions and changes are listed on their Current Conditions page. There is a separate page for Tioga and Glacier Point Roads Plowing Updates.
For more up to date information call 209/372-0200 (press 1 then 1) for a pre-recorded message of the most up-to-date conditions.
Mammoth & Devil's Postpile
The Devil's Postpile Alerts & Conditions page shows when the road down into Devil's Postpile (Agnew & Red's meadow) has opened historically as well as it's current status.
For the lakes road into town (access to Duck Pass & Mammoth Pass trailheads) check the visitmammoth tourism site. Note that there's year round parking around Tamarack Lodge, but walking the road up from there can add 2-3 miles to your trailhead each way.
SEKI
Longer term conditions and changes are listed on their Current Conditions page. They also have a specific road construction page
Eastern Sierra Ranger Districts
North to south:
- Humboldt-Toiyabe National Forest
- Mono Lake Ranger District
- Mammoth Ranger District
- White Mountain
- Mt. Whitney Ranger District
County road departments: Inyo County Public Works [see PDF at the bottom of page] & Mono County Public Works update information daily including expected opening dates and open/closed status for trailhead access roads along the Eastern Sierra.
Western Sierra Ranger Districts
- Sierra National Forest Roads
- Sequoia National Forest also Kern County Public Works Road Status & Closures
Northern Sierra Ranger Districts
Minor roads
It's often best to check with local papers and sources for updates on roads to trailheads, etc - it's important news for small mountain towns!
Looking for county sheriff's departments social media pages can be useful as well - any unplanned road closures will generally be described on them.
Local police & sherriff's departments often have fast updates on minor roads: