How Do Wildfires Start & Can We Predict Them?

As climate change makes annual wildfire seasons longer and more devastating, predicting when and where these disastrous blazes will spread has become crucial. But is it actually possible to do this? How can wildfires be predicted?

How Weather Conditions Feed the Combustion Triangle 

In order to start, a wildfire needs fuel, oxygen, and something to ignite it. In many cases, certain weather and climate conditions combine to make wildfire events more likely – affecting how they spread and how much land they burn through within short timeframes.

Lightning Creates Fires and Vice Versa

Lightning is globally recognized as the dominant natural cause of wildfire ignition, producing the largest wildfires in many regions. Scientists now understand how lightning and wildfires can function as two parts of the same self-perpetuating cycle:

  • Heat from extreme fire events evaporates moisture into the air.
  • This makes water vapor rise into the atmosphere, which often generates ‘dry’ thunderstorms, whose rainfall can evaporate before reaching the ground due to extreme heat.
  • The wildfire smoke leads to enhanced charge separation in the thunderstorm cloud which in turn creates lightning
  • Lightning strikes further dry vegetation and spark a wildfire.
  • The ignited fires produce excessive heat and more smoke pollution.
  • The cycle repeats once again.

When dry thunderstorms can unleash over 700,000 lighting strikes in a single day, wildfires become almost inevitable. Scientists predict areas burned by lightning-ignited wildfires in the Southern Eastern US will see a 30% increase by 2060.

How Do Wildfires Start?

Extreme Temperatures

As global temperatures increase, longer and more extreme heat waves contribute to an increased likelihood of wildfire events by evaporating moisture from the surface to the atmosphere as hot air can contain more moisture than cold air and thus acts kind of like a sponge. This creates a high abundance of dry vegetation, which is fuel for a wildfire. A lack of rainfall will enhance this effect and drastically increase a fire season’s severity.

Such a climate-change-induced extreme heat trend can become a regular occurrence in the coming years. Projections say that at the current rate of emissions, we could reach 2°C global warming by 2040. At which point, such extreme heat wave events, estimated to occur once in 1000 years, could repeat every half or full decade.

Scientists estimate reaching a 3°C global average warming scenario by the end of the century could impact 300 million Europeans, resulting in 96,000 annual extreme-heat-related fatalities.

Heat & Dry Weather Dehydrate Vegetation  

Burnt forest

Low humidity combined with rising temperatures helps to turn shrubbery, grass, and trees into kindling for wildfires – without sufficient moisture, dry vegetation becomes readily available wildfire fuel.

Atmospheric Instability

Unstable vertical movement of air, which occurs as hot air rises and cold air descends (much like in boiling water) can have a direct impact on a fire’s behavior:  A fire can become more intense due to unrestricted updraft air currents just as if you open the damper of your stove. The additional heat of the fire enhances this effect. And it also helps smoke pollution climb higher.

How Strong the Wind Blows

As atmospheric instability increases, stronger gusts of wind in changing directions can occur more frequently. Strong winds can then accelerate the dehydration of vegetation and carry small burning debris, helping to spark new fires and give existing ones more fuel.

Wind also supplies fire with oxygen and serves to fan wildfires, dictating fire intensity and directional spread.

The Right Stuff to Burn

The geographical features of a region also greatly impact the burning potential and likelihood of a wildfire event: In particular, forested areas can become arid and highly flammable during droughts and extreme heatwaves. Even a tiny spark can turn into a raging blaze.

While mountainous regions may be considered safer due to colder air and increased moisture at higher altitudes, climate change research suggests the high-elevation flammability barrier has been reduced, enabling forest fires to reach higher, wetter elevations.

How Do Scientists Predict Wildfires?

Due to the many environmental factors that influence fire behavior and risk, scientists involved in wildfire prediction often utilize sophisticated computer modeling to forecast the potential of a wildfire starting given different climate scenarios. By testing different values of temperature and precipitation, fire scientists can estimate where and when a fire event is likely to take place. 

How Humans Contribute to Wildfire Events

Experts estimate human-caused wildfires may be more destructive during wildfire season, as they often occur near populated areas, and drought and heat facilitate fast-burning conditions:

  • Campfires – failure to put them out properly or leaving campfires unattended means nearby vegetation can catch fire.
  • Burning Debris – byproducts of human activity such as burning yard waste can ignite dry vegetation nearby.
  • Fireworks – Popular in New Year celebrations, 4th of July, and various other holiday festivities, these pyrotechnic displays present a major wildfire risk, leading some states to ban fireworks completely.
  • Cigarettes – A decline in adult smoking helped reduce the number of annual cigarette-caused wildfires in the USA by 9%. However, extreme heat and low humidity still make vegetation highly susceptible to the smallest cigarette ember.
  • Vehicles & Equipment – Car crashes, engine sparks, and equipment failure can easily start wildfires when weather conditions facilitate fast burning.
  • Arson – Caused often by malicious intent or deceitful attempts to receive insurance compensation, hot weather conditions, and dry vegetation make arson-caused wildfires a major threat.
  • Utility Lines – Whether knocked over by strong winds or improper maintenance failing to prevent sparks, power lines can present a real danger, and have been responsible for thousands of fire events, including the Camp Fire, the deadliest wildfire in California’s history.

Information is Power

While it’s not always possible to predict the precise trigger or spark for a fire event, wildfire risk can be estimated to some extent by understanding how climate, topography, weather, and land cover impact fire behavior and the likelihood of a fire spreading.

Wildfire Tracking – A Valuable Climate Tech Tool

As climate change contributes to more unpredictable wildfire seasons, insurers, utility companies, and various other businesses and organizations can leverage wildfire intelligence to increase climate resilience on multiple fronts: prevent disruption to supply chains, protect factory and road worker lives during live fire events, and even predict wildfire risk around properties and infrastructure by analyzing historical wildfire data

Companies can also enhance consumer offerings by integrating wildfire insights with connected apps and platforms and tailoring real-time fire and smoke alerts to minimize health impacts among their users.

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Paul Walsh Weather Man
Paul Walsh

Previously at IBM and The Weather Company, I have decades of experience in helping large consumer businesses re-imagine how they systemically leverage weather and climate data in both supply and demand chain systems -- creating integrated enterprise processes that are more responsive and more resilient in the face of increasingly impactful weather conditions. My observations have been featured in the US on The Weather Channel and CNBC, & I've been quoted in The Wall Street Journal, Barron’s, and The New York Times. Connect with me!