A prescribed burn is a fire lit deliberately to clear away dry brush; fewer than 1 in 100 of these planned fires escapes to become a wildfire.
Wildfires send dangerous embers into the air that can enter a home's vents, and Total Screen's ember-resistant vent screens reduce your risk of wildfire damage.
In this guide we first explain what a prescribed burn is, then answer whether prescribed burns ever escape, then cover what the smoke means for your home, and finish with your vulnerable vents.
The U.S. Forest Service uses prescribed fire because it "reduces hazardous fuels, protecting human communities from extreme fires."[1]
What Is A Prescribed Burn?
Why are prescribed burns used at all? To remove the brush and dead wood a wildfire would otherwise burn.
A prescribed burn is a fire that trained firefighters light deliberately, to burn away brush and dead wood before a wildfire can use them as fuel.
Fire agencies use three names for the same planned fire: prescribed burn, controlled burn, and prescribed fire.[2]
Southern California chaparral, the brush a prescribed burn removes.
The crews are wildland firefighters from agencies such as the U.S. Forest Service (USFS), CAL FIRE, and local fire departments.[3]
Crews light only under weather conditions chosen in advance.
In California, a good burn day is cool and damp with light wind, which is why the Cleveland National Forest east of San Diego burns between Fall and Spring, not in August.[4]
A written burn plan sets a range for "temperature, humidity, wind, moisture of the vegetation, and conditions for the dispersal of smoke."
A day outside the burn plan's range is not a burn day, and the crew waits.
Hot, dry, and windy is a wildfire day; cool, damp, and calm is a prescribed burn day.
A prescribed burn is run by a certified "burn boss," with firefighters and fire engines standing by in case the fire moves.
After a prescribed burn, patrols stay on scene until no smoke has been visible for 24 hours.
A "pile burn" is the smaller kind of planned fire: crews cut brush, stack it in piles, and burn the piles.
A "broadcast burn" is the larger kind: fire moves across a marked block of grass or brush inside prepared control lines.
Two examples of prescribed burns and the way they are used.
Pile burns and broadcast burns both stay inside lines the crew prepared ahead of time, and a wildfire has no lines at all.
Why Controlled Burns Are Lit
The USFS lists three results of a controlled burn: it "reduces hazardous fuels," improves habitat for threatened species, and "recycles nutrients back to the soil."
"Hazardous fuels" means dry brush and dead wood that let a wildfire burn hotter and move faster.[5]
"Ladder fuels" are not ladders: the term means low branches and tall brush that let flames climb from the ground into the treetops.
The 2007 Harris Fire in East San Diego County.
The Cleveland National Forest's deputy fire chief for prescribed fire says low to moderate-intensity fires "can play a key role in keeping those same ecosystems healthy."
Some forests need fire to reproduce: the National Park Service (NPS) says "prescribed burns promote the regeneration of giant sequoias."[6]
Do Prescribed Burns Ever Escape?
Yes, prescribed burns do escape, and it is rare.
An "escaped" prescribed burn is one that crosses its control lines and becomes a wildfire.
The Government Accountability Office (GAO) reports that of the roughly 4,500 prescribed fires the USFS ignites each year, "about seven of them (less than 1 percent) escape control."[7]
The GAO found there is "rarely a single cause" of an escape, and it names stronger-than-forecast winds and dry fuels among the factors.
Five escaped prescribed burns in 26 years.
The largest recent escape was in April 2022, when two USFS prescribed fires in New Mexico merged into a wildfire that "burned more than 340,000 acres and destroyed at least 160 homes."
California had an escape this year: CAL FIRE lists the cause of the June 2026 Putah Fire, west of Winters, as "Escaped Prescribed Burn," and the fire burned 860 acres.[8]
A prescribed burn is a planned fire, not a guaranteed safe one, which is worth knowing when a planned burn appears near your home on a fire map.
To follow fires near you on a phone, read our guide to the "watch duty app."
Prescribed Burns In California And Across The Country
The Cleveland National Forest covers the mountains of San Diego, Riverside, and Orange counties, and it runs prescribed burns every year between Fall and Spring.
For the 2026 to 2027 season the Cleveland National Forest set a goal of about 4,000 acres, with 2,620 acres planned on Mount Laguna and near Pine Valley, Guatay, Campo, and Descanso.
The 2007 Witch Creek Fire in San Diego County, the kind of fire prescribed burns are meant to prevent.
Across the United States, state forestry agencies reported more than 10 million acres treated with prescribed fire in 2019.[9]
California's wildfire task force set a statewide goal of 400,000 acres of "beneficial fire" a year by 2025.[10]
Residents near a burn "may experience smoke during the prescribed burns," and areas near the work may close for several days.
What The Smoke Means For Your Home
Smoke from a prescribed burn is real smoke, and the USFS says "some smoke is inevitable and part of living in a fire-dependent ecosystem."[11]
The USFS also says, "A smaller, short-term amount of smoke today is better than long-term wildfire smoke later."
A prescribed burn is announced ahead of time, so a household can plan around the smoke.
Four smoke habits for a burn day, from the U.S. Forest Service.
On a burn day the USFS advice is to "stay indoors on ignition days, keep windows and doors shut," and to check the Air Quality Index at airnow.gov.
Wildfires send two things through the air into a neighborhood: smoke and embers.
Wildfire smoke "can travel for hundreds of miles," according to the Environmental Protection Agency (EPA), and you can smell it from a fire you will never see.[12]
Wildfire embers travel less far, but CAL FIRE describes them as "capable of igniting homes up to a mile away."[13]
Our guide to how far can fire embers travel covers the distances in detail.
Your Vulnerable Vents
"Vulnerable vents" is Total Screen's phrase for the openings on a home that let embers in: gable vents, under-eave vents, and foundation vents.
Embers blowing into an unscreened gable vent in an IBHS ember-storm test.
The Insurance Institute for Business & Home Safety (IBHS) says "windblown embers can enter attics and crawl spaces through vents."[14]
Smoke passes through any vent screen, but embers can be stopped.
IBHS research "shows that embers can pass through 1/4-inch mesh and ignite combustible materials," and 1/4-inch mesh is what most homes were built with.[15]
CAL FIRE's advice for vents is to "install 1/16-inch to 1/8-inch noncombustible, corrosion-resistant metal mesh over vents to block embers."
A 1/4-inch grid lets embers through; 1/16-inch mesh is what Total Screen installs.
Our guide to "how many homes burn down from embers" covers what federal investigators found after San Diego's 2007 Witch Fire.
Most homes have all three vent types, and each vent opens into a space full of dry wood.
Foundation vents near the ground and gable vents under the roof peak.
Ember-Resistant Vent Screens From Total Screen
Total Screen is a family-owned San Diego company that has installed window and door screens since 1994, and today we also install ember-resistant vent screens across San Diego County.
You may have heard them called ember mesh or ember vents; at Total Screen we call them ember screens.
An ember screen is a powder-coated steel mesh with 1/16-inch openings, cut to fit and fastened over the vents your home already has.
Before and after: a gable vent fitted with an ember screen.
Air keeps moving through a screened vent, and the vent itself stays in place.
Homes built before 2008 are the ones most likely to need ember screens, and our ember resistant vents home-hardening guide explains why.
A Total Screen installer screening a gable vent.
Properly screened vents may also qualify for insurance savings, which our guide to wildfire hardening discounts explains.
Total Screen works from the outside of your home, and no attic work is needed.
Before and after: an under-eave vent fitted with an ember screen.
Get A Free On-Site Vent Check
Get a free on-site vent check from Total Screen before the next fire season, and find out which of your vents need ember screens.
Call Total Screen at 1-619-871-7610, or send us a message below.
Contact Total Screen to get ember-resistant vent screens installed on every vent of your San Diego County home.
Total Screen collects public information from the U.S. Forest Service, the National Park Service, the Government Accountability Office, the Environmental Protection Agency, CAL FIRE, the Insurance Institute for Business & Home Safety, the Orange County Fire Authority, and local fire agencies, and is not a fire authority; follow your local fire agency and air district for burn notices and smoke advisories, and anyone with breathing trouble during a smoke event should speak to a healthcare provider.
Sources
- USDA Forest Service, "Prescribed Fire" (definition; burn plans "consider temperature, humidity, wind, moisture of the vegetation, and conditions for the dispersal of smoke"; benefits): fs.usda.gov/managing-land/prescribed-fire
- National Park Service, "Prescribed Fire in the National Capital Area" ("Prescribed fire is a planned fire; it is also sometimes called a 'controlled burn' or 'prescribed burn'"; staged firefighters and engines): nps.gov/articles/prescribed-fire-in-the-national-capital-area.htm
- Mattole Restoration Council release via Redheaded Blackbelt, "Prescribed Burns Planned Near Petrolia Thursday and Friday," October 29, 2026 (Honeydew Fire Company, Petrolia Fire Department, and CAL FIRE on the burn; "Qualified Burn Boss"; patrol "until no smoke is visible for 24 hours"): kymkemp.com
- USDA Forest Service, Cleveland National Forest, "Cleveland National Forest to begin Prescribed Burning," October 28, 2026 (Fall through Spring; 4,000-acre goal; Descanso Ranger District 2,620 acres and places; Scott Grasmick, Deputy Fire Chief for Prescribed Fire, Fuels and Prevention; "may experience smoke"; closures): fs.usda.gov/r05/cleveland/newsroom
- Valley News, "Prescribed Burn Underway in Cleveland National Forest; Smoke Visible South of Corona," February 13, 2026 (dry brush and "ladder fuels"): myvalleynews.com
- National Park Service, Sequoia & Kings Canyon National Parks, "Update: Prescribed Burning Planned at Grant Grove starting October 17 to Reduce Wildfire Risk," October 16, 2026 ("Prescribed burns promote the regeneration of giant sequoias"): nps.gov/seki
- U.S. Government Accountability Office, GAO-24-106239, "Forest Service: Prescribed Fire Program" (4,500 fires a year, "about seven of them (less than 1 percent) escape control"; "rarely a single cause"; 2022 Santa Fe National Forest escapes, "more than 340,000 acres," "at least 160 homes"): gao.gov/assets/870/869749.pdf. Map entries: Cerro Grande, 2000 (Wildland Fire Lessons Learned Center, lessons.wildfire.gov; 235 homes per the Associated Press, May 2020); Lower North Fork, 2012, and Pautre Fire, 2013 (Wildfire Today, citing the Colorado Department of Natural Resources review and the USFS report: wildfiretoday.com/tag/lower-north-fork-fire, wildfiretoday.com/tag/north-dakota).
- CAL FIRE, "Putah Fire" incident page, June 8, 2026 (cause "Escaped Prescribed Burn"; 860 acres; contained June 19): fire.ca.gov/incidents/2026/6/8/putah-fire
- Coalition of Prescribed Fire Councils and National Association of State Foresters, "2020 National Prescribed Fire Use Report" (10,003,541 forestry and rangeland acres treated with prescribed fire in 2019): archive-nwfsc.forestry.oregonstate.edu (PDF)
- Office of Governor Gavin Newsom, "Governor's Task Force Launches Strategic Plan to Ramp Up Wildfire Mitigation with Prescribed Fire Efforts," March 30, 2022 (400,000 acres of beneficial fire annually by 2025): gov.ca.gov
- USDA Forest Service, San Juan National Forest, "Smoke and Prescribed Fire" ("some smoke is inevitable"; "A smaller, short-term amount of smoke today"; ignition-day advice; AirNow): fs.usda.gov/media/237799
- U.S. Environmental Protection Agency, "EPA and Forest Service Release Updated AirNow Fire and Smoke Map," September 5, 2024 (wildfire smoke "can travel for hundreds of miles"): epa.gov/newsreleases
- CAL FIRE, Ready for Wildfire, "Hardening Your Home" (flying embers "capable of igniting homes up to a mile away"; "Install 1/16-inch to 1/8-inch noncombustible, corrosion-resistant metal mesh over vents to block embers"): readyforwildfire.org
- Insurance Institute for Business & Home Safety, "Wildfire Research Fact Sheet: Attic and Crawl Space Vents" ("Windblown embers can enter attics and crawl spaces through vents"; "embers can pass through 1/4-inch mesh and ignite combustible materials"): class.ucanr.edu (PDF)
- Orange County Fire Authority, "Ready, Set, Go: Vents" ("most homes are built using 1/4-inch screens"): ocfa.org (PDF)