Backpacker’s Guide to Tracking California Wildfires

Fires one year; huge amounts of snow the next.  You never know what Mother Nature is going to throw our way. I’ve never spent as much time immersed in fire data trying to figure out where smoke-free backpacking routes might be as I have the past few years. If the predictions of experts hold true, we’ll be doing a lot more of that in the future as our fire season spreads across the calendar. I now have a set of go-to websites where I cross-reference wildfire activity and air quality.

Smoky Juniper Lake

Smoke from the Carr Fire hangs over Juniper Lake, Lassen Volcanic National Park

California Fire Season

To put fires into context, it is important to understand that wildfires have always been a part of the California ecology. Fire plays an important role in maintaining healthy ecosysytems but can also cause great harm. In the past, fall saw destructive fires from the so-called Santa Ana (in Southern California) or Diablo (in Northern California) winds—hot dry winds that reverse direction from the usual marine flow and blow from the dry Central Valley to the west, often leaving a path of burned destruction in their wake. I now live in a Diablo wind-generated burn zone in Sonoma. The Wine Country Fires (LNU Complex) started on October 8, 2017 and burned 110,000 acres and 6,957 structures in Sonoma and Napa Counties. Forty-two people died in Northern California fires (22 in Sonoma alone) that year. Since then, huge fires have become the norm and records fall with terrifying regularity.

That doesn’t mean summer doesn’t usually see significant wildfire activity, especially with California’s normal cycles of multi-year droughts alternating with wet years. Summer wildfires usually burn more slowly and a “let burn” policy in rugged, wild terrain has been in place for decades. Santa Ana/Diablo fires, on the other hand, can burn quickly and be more destructive as they burn through developed areas along the coast (e.g. Wine Country fires, Oakland fire, Cedar Fire, Laguna Beach Fire). To add another word to our growing vocabulary, a foehn wind is a dry, warm, down-slope wind that occurs on the downwind side of a mountain range.

Both summer and Santa Ana/Diablo fires have been increasing in number and severity as California gradually gets warmer and drier. Summer fires generally burn between June and September while Santa Ana/Diablo fires can occur in October or later. We’re beginning to understand that destructive fires can occur at any time throughout the year.

Hiking through a burn zone from the Reading Fire (2012) near Feather Lake with smoke from the Carr Fire (2018), Lassen Volcanic National Park

Tracking Resources

There are many websites that aid in tracking fires and their aftermath. The ones that I used the most are listed below. I shared these on hiking forums over and over in 2018 as hikers scrambled to develop Plan B, Plan C or were forced to cancel their plans, some of which were in the making for over a year. Many John Muir Trail and Pacific Crest Trail hikers had to figure out alternate trailheads and exits while contending with the effects of smoke. Some lucked out and found slices of clear air while others left the trail, worried about the health effects of breathing particulate matter or being caught in the path of a fire.

Current Fire and Smoke Tracking

  • InciWeb is a US Forest Service information management system that provides a central location for identifying incidents and maps.
  • CalFire, the California Department of Forestry and Fire Protection, fights fires and provides  emergency services in some counties via contracts with local governments. You can locate information about fires on a mapping and incidence tracker.
  • WatchDuty is a mobile app that covers vegetation fires in high risk areas in California. You can choose the counties you want to follow. 
  • AirNow is a government resource where you can enter a location and find the air quality. This site displays the Air Quality Index (AQI), which is based on five different pollutants in the U.S. Values are averaged over time.  One of  pollutants in the AQI is the PM2.5, which they report separately. AirNow has an app (Apple and Android). The EPA AirNow app is the most accurate. They also have a Fire section
  • Purple Air  has graphics that make it easy to assess air quality across the state. Color-coded circles indicate whether air quality is good (green), moderate (yellow or orange) or significantly poor (red, purple and burgundy). Click on a circle to get detailed air quality information based on particulate matter, specifically PM2.5. PM2.5 refers to atmospheric particulate matter (PM) that has a diameter of less than 2.5 micrometers and is the prominent component of wildfire smoke. Learn more about PM2.5 here. The Purple Air site can be configured to display different pollutant levels.Data show that Purple Air can run a little high when compared to official EPA numbers, but provides useful data points that are available in real time. The low cost of Purple Air sensors also means that sensors are widely distributed across certain regions. Anyone can purchase a sensor and to add to the network.
  • Blue Sky is a site that models the location and direction of spreading smoke. This is helpful when planning a wilderness route. Smoke from the Ferguson Fire in Yosemite often drifted northeast into the Tahoe Basin, for example. For our Canadian friends, Blue Sky Canada has a separate site.
  • California Smoke Information is an inter-agency effort to coordinate and aggregate data. They provide a effective visual that indicates intensity and direction of smoke.
  • Firemappers has crowd-sourced and incident information in a mapping tool from ArcGis.
  • CalTopo is a free mapping program used by many backpackers to create their own routes. In the Map Overlay section there is an option to check Fire Activity to get current fire maps or Fire History for maps of previous fires.  The red dots mean there is active heat detected from satellites. The orange or yellow dots mean the heat is older.
  • GaiaGPS is a trail map app that offers free smoke forecast maps (see article describing the maps).
  • Twitter is often the best source of information in the first few hours of a new wildfire. CA Fire Scanner is a good feed to follow or you can see the sites I follow in my Fire, Emergency, Weather List. Once the fire is named, it’s easy to find info using #nameoffire (e.g. #washburnfire).
  • A technical note about the satellite system used to map active fires per  Joseph Elfelt @MappingSupport (Twitter) says: “There are 2 MODIS satellites and 2 VIIRS satellites. The MODIS/VIIRS satellites make a total of 8 passes per 24 hours. For the West Coast, very rough timing is midnight to 3am (4 passes) and noon to 3pm (4 passes). It takes NASA ~3 hours to process the raw data before it can be displayed on any map. Usually by 7am Pacific Time the maps are showing all the MODIS/VIIRS data that is available until sometime after 3 pm. Hotspot locations are approximate and sometimes the data is ‘false positive’. The CalTopo fire map can display data from the GOES satellites. That data (large colored squares) is refreshed very frequently but the location is generalized over a much larger area compared to MODIS/VIIRS.”

Updates Via Satellite Messenger Device

You can get updates about fires and air quality within 50 miles of your location by texting your GPS coordiates on your satellite messenger device (Garmin InReach, Zoleo, SPOT) to (765) 55-FIRES (that’s 765-553-4737). See for more information on how this works. 


Webcams are useful for visualizing the sky in real time. This is useful when evaluating smoke and identifying fire activity.

Burn Zone Map

Being able to identify the perimeter of previous burn zones is valuable when planning a route. Walking through short segments of burn zones can be educational and interesting but if most of your planned route is in a scorched area, it can be unappealing. Entering Burn Area: Yosemite After the Fire, a New York Times article, describes a hike through a burn zone.

  • CalTopo  is a robust mapping application. Click on “MapBuilder Topo” and select “Fire History.” Colored outlines will appear with the name and year of the fire. Click on “Fire Activity” to see current fires. Here’s an example of a CalTopo route I hiked in Lassen Volcanic National Park. We did a day hike to Feather Lake and yes, indeed it was scorched and stark from the Reading Fire.
  • The San Francisco Chronicle maintains a California Fire Tracker with an interactive map of current and past fires.

Feather Lake after the Reading Fire (2012) with smoke from the Carr Fire (2018), Lassen Volcanic National Park

Health Effects of Wildfires

I have become increasingly concerned about the effects of hiking in smoky conditions. The fine particles (PM2.5) are the biggest problem. Burning eyes, a runny nose, cough, phlegm, wheezing or difficulty breathing are symptoms that can result from breathing fine particles. Those with heart or lung problems can be impacted even more.

A comprehensive review of the health effects is beyond the scope of this article but several links are provided for those who are curious. Common sense would indicate that engaging in activity that requires deep inhalation of particulate matter into the far recesses of the lung and having 24-hour exposure is not a good idea.  To briefly summarize the data in the references below, smoke is not good for your health.

N95 Mask

Face masks can provide some protection. A simple dust mask is not adequate. N95 masks are recommended as they filter 99% of airborne particles. The mask must fit properly and snugly to be effective. The CDC offers an illustration about how to wear masks. The N95 masks can be worn for at least 8 hours, according to the CDC, perhaps longer depending on the circumstances. Hiking for an extended period of time would not be comfortable but with the increasing incidence of fires, adding an N95 mask to your emergency kit may be prudent. Reusable N95-N99 masks are available (see Cambridge Mask, technical specs here), which may be more practical to pack.

N95 mask (L) and reusable mask

Avoiding Injury in a Wildfire

A more acute concern if you’re on the trail in the vicinity of a wildfire is safety. Fires can move quickly and move faster when moving uphill than downhill. Avoid being on a ridge with a rapidly approaching fire from below. Watch the sky and assess the velocity and direction of smoke, talk to other people on the trail, share information and obey closure notices and any instructions from officials. Leave your itinerary with rangers, friends and in your vehicle at the trailhead. If you have a satellite communication device with two-way communication, use it to get up-to-date information. Officials have various ways of communicating with backcountry travelers and I have seen several reports of air evacuations (though of course, there is no guarantee that resources will be available or that weather or fire conditions will cooperate). Don’t do anything that would put personnel at risk such as ignoring closure signs or getting caught in a fire zone when you could reasonably avoid it.

The Pacific Crest Trail Association (PCTA) has three informative articles

Preventing Forest Fires

Finally, I would be remiss if I didn’t address prevention of forest fires. Though lightning strikes can and do cause wildfires (e.g. Rough Fire, 2015, 257,314 acres burned in Sequoia Kings Canyon NP), the vast majority are caused by humans. The Rim Fire in 2013 was caused by an illegal campfire. The Carr Fire was caused by sparks resulting from a flat tire (the tire rim scraped the asphalt and threw off sparks). The Ferguson Fire in Yosemite was caused by a faulty catalytic converter in a passing vehicle.

The first recommendation is to not build campfires. Period (sort of–the only exception would be if it’s cold and wet and someone has hypothermia).  We stopped building campfires years ago because we were so afraid of what wildfires were doing to our state and now we just don’t think about them anymore. It makes sense to urge caution when using stoves but I rarely hear about major fires being started by stove use.

Fire Information, PCTA

Though wildfires have always played a role in California ecology, we can expect stronger and more frequent fires. By using available resources and having flexible plans, backcountry enthusiasts can plan enjoyable, safe outings.

Mt Islip, near the PCT, burned in the Bobcat Fire (2020) (Kenny Meyer)

Recent Fire Seasons

In July, 2018, 17 major fires burned across California, with additional fires in Oregon, Washington, British Columbia and Colorado. Unlike summer fires in the past, they seemed to explode in size and number, increasing significantly every day that they burned. These fires generated tremendous plumes of smoke that spread across the west.  In July and August, it didn’t seem like there were any wildlands where one could find clean air other than the coastal areas.

To illustrate the size and scope of just a few of these fires, here are some stats. The Ferguson Fire  near Yosemite started on July 13, 2018, burning 96,901 acres. Parts of Yosemite were evacuated and Yosemite Valley closed from July 25 to August 10. To illustrate how fast it grew, it spread to 828 acres in just the first 24 hours. The Carr Fire near Redding, which started on July 23, 2018, ultimately burned 229,651 acres and 1,079 residences. The Mendocino Complex Fire started July 27, 2018, finally burning 459,123 acres.  Within the first 24 hours, it burned 42,017 acres. The Donnell Fire near Sonora Pass started August 1, 2018 and burned 36,450 acres.

Fall wasn’t much better in 2018 with the disastrous Camp Fire in Paradise that burned more than 150,000 forested acres and 18,000 buildings. At its peak, it raged forward at an acre per second. Tragically, more than 80 bodies were recovered. This fire broke all kinds of records and was notable for how late in the season it was. It started on November 8 with a foehn wind blowing from the east, well after our winter rains should have started. Hikers heading into the wilderness in autumn are advised to be aware of the potential danger of being caught in such a firestorm, especially during red flag warnings.

The 2018 California wildfire season was so bad that it has its own Wikipedia entry. A total of 8,527 fires burned 1,893,913 acres. On August 4, a national disaster was declared in Northern California.

The 2020 California Wildfire Season was another record setting wildfire year with 9,639 fires burning 4,397,809 acres in California (4% of California’s land mass). There were a few notable highlights, including a rare ban on ALL stoves in the backcountry (anything that ignited) in ALL national forests in California in the fall. The Glass Fire in Napa and Sonoma was notable for it’s speed, flaring up from 20 acres to 11,000 acres in one day. 


Boat, smoky skies

China Camp, Sunrise Nov. 9, 2018 Camp Fire (Steve Ziman)

Golden Gate Bridge Sunrise on Nov. 11, Camp Fire (Steve Ziman)

Rat Rock Sunrise, Aug. 7, 2018 (Steve Ziman)

Sunrise San Pablo Bay, Tubbs Fire Oct 12, 2017 (Steve Ziman)

Burn from the Rainbow Fire (1992) near Red’s Meadow through smoke from the French Fire (2014) on the John Muir Trail