How do wildfires start?

As of this writing, there are 900 wildfires burning across Canada. Some are contained while others are out of control.

But all are dangerous.

Wildfires can occur naturally, most often due to lightning strikes and, in very rare cases, spontaneous combustion.

However, more than 50 per cent of all wildfires in Canada are caused by humans.

For a wildfire (or any fire) to burn, it needs three things:

1. Fuel: Combustible material that can burn, such as trees, dry leaves, grass, brush, deadfall and wood.
2. Heat: An external source that ignites the fuel. This can be natural (such as lightning strikes) or artificially made (such as discarded cigarettes, sparks or embers).
3. Oxygen: We need it to live. Wildfires need it to maintain combustion, which allows the fire to start and keep burning.

This is called the “fire triangle.” To stop a wildfire, one of these three elements must be removed.

However, the best way to stop a wildfire is to, if possible, prevent it from happening in the first place.

What causes wildfires?

Lightning, mostly.

Lightning is unpredictable. And each year it’s responsible for about 46 per cent of Canadian wildfires. These fires go on to burn roughly 2.5 million hectares of land.

For context, the province of Prince Edward Island (P.E.I.) is approximately 570,000 hectares. Each year, lightning-caused wildfires burn an area roughly 4.5 times the size of P.E.I.

Here’s how it happens:

1. Strike and ignite: When lightning strikes, it transfers heat and electrical current into whatever it hits, such as trees or dry grass. Any moisture is vaporized and any nearby vegetation ignites.
2. Smoulder: Most lightning strikes don’t burst into flames immediately. The strike creates a smoulder (heat trapped inside things like hollow tree trunks) which is slow-burning and tough to detect.
3. Smouldering continues: Smolder can persist for hours, days, even weeks as it burns through fuel. The ignition from step one has occurred, but the visible fire hasn’t emerged. Yet.
4. Transition to open flame: As the smoulder reaches the surface and is exposed to more oxygen, it bursts into an open flame. From there, fuel, wind and terrain allow it to grow and spread.

Lightning is hot (around 30,000 degrees Celsius) and narrow (roughly two inches). All that heat, nearly five times hotter than the sun’s surface, is packed into a vessel the width of an iPhone.

Other natural causes of wildfires

While lightning is the dominant natural cause of wildfires, there are other, rarer ways for wildfires to ignite:

• Spontaneous combustion: Things like dry vegetation or decomposing plants can, under the right conditions, slowly generate heat through microbial or natural chemical activity until they self-ignite.
• Volcanic eruptions: Lava flows, hot ash and volcanic gases can ignite nearby vegetation. This is very rare and limited to volcanic regions. Canada has five such regions in British Columbia and Yukon.
• Rockfalls or landslides: Rocks striking together as they tumble down a hillside or mountainside can produce sparks that ignite extremely dry grasses or vegetation that’s nearby.
• Meteorite impacts: Rare, but possible. Meteorites can generate intense heat and ignite vegetation or trees at the impact site.

How do wildfires start from human activity?

Human activity accounts for:

• Roughly 50 per cent of all wildfires in Canada (in the U.S., that number is 85 per cent ).
• More than 2,700 wildfires in Canada each year.

A main culprit is the deliberate burning of organic debris, such as yard waste, leaves, branches and grass.

Before continuing, no, that does not mean people are transporting yard waste to the middle of the back country and setting it ablaze. It’s usually done in private fields or yards. But the reasons this causes wildfires are:

1. It’s a common practice: Many landowners and farmers burn agricultural debris every year.
2. Size: Debris fires are bigger than campfires. If it is not contained or controlled, it can quickly spread. Especially if the wind picks up.
3. Travelling embers: Most embers land near their source flame. In extreme, everything-has-to-be-just-right conditions, it’s possible for embers to travel—and start—wildfires up to 40 kilometres away.
4. Changing weather conditions: A safe burn can suddenly become dangerous as temperatures rise, humidity drops or winds increase.

PSA: How to burn brush safely

Landowners and farmers burn brush and debris to clear land and, ironically, reduce potential fuel sources for wildfires. Permit requirements vary by region or time of year, but the following safety tips always apply:

1. Check local weather conditions and avoid burning during hot, dry or windy days.
2. Burn only a single pile at a time and ensure piles are kept small and manageable.
3. Have a hose, water source and tools such as a shovel or rake within reach to contain and control the fire if conditions change.
4. Never leave the fire unattended until it is fully extinguished and cool to the touch.

Other human causes of wildfires

• Unattended campfires: Even if a campfire appears to be extinguished, campfire safety says it isn’t until it’s cool to the touch. Embers can drift into dry brush, deadfall or grass and ultimately cause ignition.
• Equipment use: In physics, a hammer is a simple machine. In 2018, a man used a hammer to drive a metal stake in the ground. It generated a spark which lit a wildfire that burned 410,000 acres.
• Fireworks: A smoke bomb used in a gender reveal party sparked the 2021 El Dorado wildfire in California. All told, 9,300 hectares, 20 homes, numerous buildings and one firefighter were lost in the blaze.
• Recreation: Portable grills, stoves and lanterns are essential for enjoying the outdoors. But they must be fully extinguished and turned off before being left unattended.
• Discarded cigarettes: Not as common as one would think. But still a potential source for wildfires.
• Arson: Sigh. Using Alberta as a baseline, it’s estimated that between five and 10 per cent of wildfiresvare caused byvarsonists. The silver lining is that arson accounts for less than one per cent of all wildfire damage.

Something to consider regarding how wildfires start

Most wildfires don’t start with the actions of negligent or careless campers.

They start from the unexpected power of a lightning strike. Or the unintended result of using tools as powerful as a chainsaw or as rudimentary as a hammer. Or from a sudden wind shift that catches a responsible landowner off guard.

And usually, they start slowly and quietly.

Smoulders that silently generate heat for days. Tiny embers that float and land on dry ground. A spark that exists for only a fraction of a second but leaves behind a fire that can burn for weeks.

Lastly, while lightning is impossible to predict or control, many human-caused wildfires can be prevented by taking simple precautions beforehand.

The impact of climate change on wildfires

Does climate change start wildfires?

Not directly, because climate change doesn’t:

• Direct lightning where to strike.
• Leave campfires unattended.
• Force burning brush piles to escape control.
• Cause sparks to fly from machinery.

What climate change does is create conditions for wildfires to burn hotter, grow larger and become more destructive once they ignite.

That spark from that hammer mentioned earlier? If it falls on damp grass, it likely fizzles out harmlessly.

That same spark landing on weeks of hot, dried-out vegetation? Much more likely to ignite a wildfire.

We know that climate change contributes to hotter, drier conditions. Shorter winters, reduced snowpack, earlier snowmelt and longer summers also lengthen and strengthen the wildfire season (typically from April to October).

With drier, more combustible fuel and more time to burn, the result isn’t necessarily more wildfires.

It’s more opportunities for small wildfires to become very large, very quickly.

How World Vision Canada supports victims of wildfires

Preventing wildfires matters. But when prevention isn’t enough, World Vision Canada is there to help communities recover.

First in, last out

• When disasters strike in the countries where World Vision works —including devastating wildfires—we respond with disaster relief within the first 72 hours to feed, comfort and protect those most impacted. And we don’t leave until the community recovers and rebuilds. Even if it takes years.

Providing safety and comfort for children

• The Chilean wildfires of January 2026 left 20 people dead, more than 21,000 displaced and over 4,000 homes destroyed. World Vision provided Child-Friendly Spaces to keep children safe and provide mental health support during the crisis.

Every wildfire has a beginning

Earlier, we introduced the fire triangle: fuel, heat and oxygen.

Every wildfire needs those three elements. And while we cannot control where lightning strikes, we can control the actions that lead to human-caused wildfires.

Keeping water nearby as you work with tools. Ensuring a campfire is fully out before walking away. Waiting one more day for safer, more favourable conditions to burn brush.

Every wildfire has a beginning. A spark. A source of ignition.

And understanding that beginning is key to preventing the next one.