The 4 Stages of Wildfire Explained

Understanding the stages of a wildfire can turn what looks chaotic into a recognizable process. Panic or feelings of helplessness when faced with the destructive power of a fast-moving wildfire are understandable. Yet there are four distinctive wildfire stages, and how you react at each of them can make all the difference.

Below, we share the details you need to know to reduce the risk of serious damage to or loss of your home.

What are the 4 stages of wildfire?

The four stages of wildfires are distinct steps each blaze goes through. The speed at which they develop depends on weather, terrain, and fuel availability.

Wildfires don’t just suddenly become full disasters out of nowhere. By the time you see them on the news or at the edge of your community, they have already gone through some of the four stages of fire development.

Here’s a closer look at each of the phases of a wildfire, with insights into how they develop and spread:

1. Incipient stage

The incipient stage of wildfire, also called the ignition or start phase, is the moment a heat source sparks a fire. It can be as seemingly insignificant as a discarded cigarette butt or windblown ember, or as large as a lightning strike or fallen electrical wire.

During the incipient stage, the fire is small and doesn’t throw off much heat or smoke. If left burning with enough fuel and a bit of wind, it can quickly advance to the next stage.

If you see a fire start, call 911 immediately, even if it’s small enough to put out with a bucket of water or a handheld fire extinguisher. In most situations, you should stay a safe distance, keep roads clear, and be ready to evacuate.

2. Growth stage

The growth stage of wildfire, also called the spreading or burn stage, is when the fire expands, sometimes rapidly. You may see tall flames, thick smoke, and burning embers in front of the main fire. This phase lasts between one minute and several hours, depending on the availability of fuel and the strength of the wind.

A dangerous event called a flashover is possible. This is when the right combination of heat, oxygen, and fuel can cause a nearby tree or house to suddenly erupt in flames. This almost-instantaneous phenomenon leaves little time for escape.

Growth stage fires can burn hot, easily exceeding 1,400°F (760°C). Don’t even think of trying to fight it on your own. Shut off gas lines, remove propane tanks on your property, and clear out flammable items like toys and patio furniture. Be ready to evacuate.

3. Fully developed stage

The fully developed stage of a wildfire is when the fire is at its peak heat and intensity. It’s sometimes called the fully involved, free-burning, or peak-burning stage. 

During this stage, flames are towering, producing dense smoke and extreme heat. You might even see fire tornadoes. Temperatures are intense, exceeding 1,500°F (815°C). This is the most dangerous and destructive stage, unsurvivable for any structure or living thing. If you are in its path, evacuate immediately.

Firefighters struggle to slow its advance at this stage. They may set small, controllable fires in its path to remove as much fuel as possible. Their goal is containment. This stage can last for hours or days, becoming more dangerous and unpredictable as it goes on. At this stage, the fire continues until it runs out of fuel or rain extinguishes it.

4. Smoldering stage

The smoldering stage of a wildfire, also called the decay or burnout stage, occurs when active flames have died down. However, heat and combustion of any remaining fuel continue. Embers still glow and light smoke rises. You may observe a flare-up here and there as unburned stumps, roots, and debris ignite.

While still a hot 600°F (315°C), the fire is not as intense. This phase can last for days or weeks, as long as some fuel remains and the weather stays dry. Firefighters work to fully extinguish the blaze, eliminate any remaining fuel, lower temperatures, and keep the fire from flaring up again.

The smoldering stage of a wildfire is still dangerous, as wind can catch embers and spread the fire to fresh fuel. It can all too easily blaze back into the fully developed stage. Make sure your property has been fully inspected by professionals who can detect hidden hotspots before you return.

Which wildfire stage is the most dangerous to homeowners?

For homeowners, the most dangerous stage of a wildfire isn’t just when flames are raging, but also during and after. From the moment a fire ignites, wind-borne embers can travel ahead of the blaze, land on vulnerable surfaces, and start secondary ignitions. Even after the main fire front has passed, smoldering embers can persist in roofs, vegetation, gutters, or debris, renewing risk.

Approximately 90% of homes destroyed by wildfire are set ablaze by burning embers. Homes within the wildland-urban interface (WUI) are most at risk from flying embers, With strong winds spreading them far in advance of the main fire. Staying protected means addressing that danger before it ever reaches your walls or roof.

The Frontline Wildfire Defense System automatically detects unseen embers and extinguishes them, so you don’t have to wait and worry. While no system can protect against a full blaze, installing defenses like Frontline can harden your property and lower the risk of ignition during the ember-driven and smoldering phases of a wildfire.

According to Harry Statter, Frontline CEO, “Windborne embers, the leading cause of home loss in wildfires, can be countered with smart defense systems. Once a structure ignites, the chances of saving it drop dramatically. Prevention requires far less water than attempting to extinguish an active structure fire.“

What affects the progression of the 4 stages?

How a wildfire goes through the four stages of fire development varies. Several factors affect how fast it gets going, how far it spreads, and the intensity of the burn.

• Fuel: Dry grass, pine needles, and dense forest fuel its growth.
• Weather: Hot, dry periods dry out vegetation, making it more flammable. High winds create a hotter fire and send burning embers miles ahead of the main blaze.
• Topography: Fire moves faster uphill. Burning debris can roll downhill, setting new fires as it goes.

Beyond the 4 stages: management and control

The four stages of wildfire development help you understand a wildfire lifecycle, but you may hear other classifications. These include:

• Out-of-Control (OC): The fire is actively spreading. 
• Being Held (BH): Firefighters are making progress, but the fire is still active. The focus is on fire suppression.
• Under Control (UC): The fire is fully contained.
• Out (OUT): The fire is extinguished, but dangers remain for homeowners.

In all conditions, you can take proactive steps. Instead of relying on stretched-thin fire crews or a lucky change of wind direction, put active wildfire protection in place to save your home.

What can you do to prevent your house from igniting?

It’s much easier to stop a fire at the earliest stage than to fight it once flames have fully developed. You can reduce the risk of ignition by hardening your property with fire-resistant landscaping, keeping flammable materials away from your home, replacing combustible roofing, and eliminating spots where embers can get trapped. Keeping clear access to roads, water, and other essentials also helps ensure you’re prepared in case evacuation becomes necessary.

The Frontline Wildfire Defense System allows you to take a proactive approach to wildfire defense. It continuously monitors your property for embers and automatically applies water and fire-retardant foam when fire is detected within seven miles of your home, preventing ignition and giving your property an extra layer of protection when it matters most.