Wildfires are a growing threat, and 2025 has been no exception. According to the National Interagency Fire Center, 3,959 wildfires have burned 88,873 acres of land across the United States so far. This is above the 10-year average of 3,715 wildfires and 72,837 acres burned. Fire counts are up, and the ones that burn are scorching more land than ever. 

But how do wildfires start? What makes them spread so fast? From lightning strikes to campfires gone wrong, wildfires are fueled by a mix of nature and human activity. Let’s break it down and see how to reduce the risks.

What Is a Wildfire?

A wildfire is an uncontrolled fire that spreads through forests, grasslands, and other wild areas. It can start from natural causes, like lightning, or human activities, such as campfires and arson. Once ignited, a wildfire can spread fast because of dry vegetation, wind, and high temperatures.

There are different types of wildfires. Ground fires burn slowly below the surface in thick organic soil, while surface fires move through dry leaves, grass, and fallen branches. The most intense are crown fires. They race through treetops and are nearly impossible to stop. Some wildfires combine multiple types that make them more destructive.

Weather plays a huge role in how wildfires spread. Strong winds push flames forward, high temperatures dry out vegetation, and little rainfall turns forests into kindling. Steep terrain can also make fires worse, as flames move uphill faster than they burn downhill.

However, wildfires aren’t always bad. Some plants, like certain pine trees, need fire to release their seeds. Fires also clear out dead vegetation to make room for new plant growth. Unfortunately, climate change has created conditions for bigger, more intense wildfires. With longer droughts and hotter summers, fires are burning more land and lasting longer than they did decades ago.

Wildfires also affect people. They destroy homes, force evacuations, and create toxic smoke that can cause serious health issues. For instance, California’s 2018 Camp Fire wiped out 90% of homes in Paradise and killed 85 people.

Understanding how wildfires start and spread helps protect communities and manage fire-prone landscapes. While we can’t completely stop wildfires, we can take steps to reduce fire risks and lessen their impact.

Effects of Wildfire

Wildfires are becoming more frequent and intense, and their impact goes far beyond just burning trees. They affect many things, including the air, water, wildlife, and local economy. Here’s a breakdown of the effects of wildfires on people and the environment: 

1. Horrible Air Quality

Wildfires release massive amounts of smoke, fine particulates, and harmful gases into the air. As a result, the air is dangerous to breathe even from hundreds of miles away. The tiny particles in smoke can cause burning eyes, sore throats, and coughing. In addition, some research suggests that wildfires are erasing decades of progress in air quality improvements. Massive fires that burn for days or weeks pump pollutants into the air and affect millions of people.

2. Health Risks

Wildfire smoke is a real health hazard. Breathing in fine particulates from smoke can lead to serious lung and heart problems. The smoke can irritate the nose, throat, and lungs. It can also lead to more severe health problems, especially for people with asthma or lung disease. 

Wildfires have also been linked to heart attacks, strokes, and heart failure because of reduced oxygen levels and increased stress on the cardiovascular system. Children, pregnant women, and the elderly are especially at risk because they struggle more with smoke exposure.

3. Water Contamination 

Wildfires don’t just destroy land. They also affect water sources. When fires burn, they release harmful chemicals, ash, and heavy metals. These substances wash into bodies of water and pollute what we drink. Ash and debris from burned areas can also clog water treatment systems, making it harder to provide safe drinking water. 

On top of that, vegetation that normally absorbs rainfall is gone after a wildfire. This increases the risk of flash floods, mudslides, and erosion, contaminating water more. It can take years for watersheds to recover from fire damage, so communities will struggle with water quality issues long after the flames are gone.

4. Property Loss

Wildfires can destroy homes, farms, businesses, and towns in their path. They burn millions of acres every year in the US, and the 2020 fire season alone caused structure fires that destroyed 9,630 residences, 7,255 minor structures, and 1,119 commercial or mixed residential structures.

Aside from rebuilding costs, businesses suffer when towns are evacuated or tourism declines due to fire damage. Insurance rates also skyrocket in fire-prone areas. Farms and ranches take a huge hit from wildfires by losing crops, livestock, and valuable farmland. These can take years to recover from. 

5. Ecosystem Disruptions

Wildfires force animals to leave their habitats, which leads to mass displacement or death. Species that rely on dense forests for survival suffer the most. 

Without trees and plants to hold soil in place, burned areas become prone to landslides and erosion. As a result, it’s harder for forests to regrow. On top of that, pollutants from burned forests can leach into rivers and lakes, affecting fish and other aquatic life.

6. Power Outages

Wildfires don’t just burn trees and homes. They also damage infrastructure and cause major disruptions to daily life. Fires can destroy power lines, cell towers, and fiber-optic cables, making it difficult for emergency responders and residents to communicate. 

Utility companies also usually shut off electricity in fire-prone areas to prevent power lines from sparking new fires. This leaves thousands of homes without power, sometimes for days. Roads and highways can also be shut down due to smoke, fallen trees, or fire damage, making evacuation and emergency response more difficult.

7. Climate Change

Wildfires contribute to climate change by releasing massive amounts of carbon dioxide (CO2) and other greenhouse gases into the atmosphere. Fires destroy trees that normally absorb CO2, adding more CO2 to the air. Rising temperatures and prolonged droughts also mean wildfire seasons start earlier and last longer. The more wildfires we have, the more greenhouse gases we release, which in turn makes conditions hotter and drier for more wildfires.

8. Economic Costs 

Wildfires cost entire regions and countries a lot. Treating wildfire-related respiratory and heart conditions costs billions of dollars each year. Communities affected by wildfires often spend years recovering, with billions spent on reconstruction. Local economies suffer more when businesses shut down, tourism declines, and residents relocate.

How Do Wildfires Start?

Wildfires start in different ways, but most are caused by people. According to National Geographic, about 85% of wildfires in the US occur because of human actions— unattended campfires, discarded cigarettes, arson, and sparks from power lines or machinery. The rest are usually sparked by nature, with lightning being the biggest culprit.

For a fire to ignite and spread, three things need to be present: fuel, heat, and oxygen. This is called the fire triangle. Fuel can be anything that burns—trees, dry grass, shrubs, or houses. Heat sources include lightning, the sun, campfires, and electrical equipment. Oxygen, of course, is always around in the air. When these three elements come together under the right conditions, a wildfire can take off and spread fast.

Dry weather and drought also make things worse. When there's little rain, plants dry out and become perfect fuel. In places like California, hot, dry winds help fires spread quickly and turn small flames into major fires. Strong winds can also knock down power lines, which can send sparks flying into dry vegetation.

Understanding how wildfires start is key to preventing them. While we can’t control lightning, we can reduce the risk by being more careful with campfires, cigarettes, and other fire hazards.

Causes of Wildfires

Wildfires can start in many ways. But most of the time, humans are the reason they happen. Let’s break down the most common causes and how they lead to these destructive blazes below: 

Burning Debris 

Burning debris is the top way humans start wildfires. It accounts for 29% of wildfires. People light up leaves, branches, or other waste but don’t always take the right precautions. If the fire isn’t contained properly, wind can carry embers and spread fires elsewhere.

Prescribed burns, which are controlled fires set by professionals to clear out flammable vegetation, can also get out of hand. If conditions aren’t perfect (for instance, too windy or dry), these burns can turn into full-blown wildfires. That’s why permits and careful planning are so important.

Arson 

Some wildfires start on purpose. People set fires for different reasons—revenge, crime cover-ups, or just for the thrill. Arson accounts for about 21% of wildfires every year. It leads to massive damage, loss of life, and legal consequences. 

Equipment & Vehicles 

About 11% of wildfires start from sparks created by machines and vehicles. Chainsaws, lawnmowers, and welding equipment can send out sparks that ignite dry grass or leaves. Even cars can start fires if a hot exhaust pipe touches dry vegetation. Dragging chains, exposed wheel rims, or faulty brakes can also produce sparks.

Lightning 

Not all wildfires are human-caused. Lightning is the most common natural source of wildfires. It causes about 10% of wildfires annually. 

When lightning strikes trees, dry grass, or power lines, it can spark a fire. These fires are especially dangerous because they often happen in remote areas, making them harder to control. In 2020, over 12,000 dry lightning strikes caused over 650 wildfires in California. They burned more than 1.5 million acres and forced hundreds of thousands to evacuate.

Campfires

Campfires are relaxing but account for about 5% of wildfires. A single ember can smolder for hours and reignite into a larger blaze. Campers should always check fire regulations, start fires in safe areas, and completely put them out before leaving.

Fireworks

Fireworks are fun, but they’re also a major wildfire risk, especially during dry seasons. Even small fireworks like sparklers can start fires if they land on dry grass or leaves. They cause about 5% of wildfires. Fireworks also cause a significant increase in wildfire ignition during the fourth of July. 

Smoking

Discarded cigarettes might not seem like a big deal, but they cause about 2% of wildfires. When someone tosses a lit cigarette onto dry ground, it can smolder and catch fire. 

Volcanoes

While not as common, volcanic eruptions can also start wildfires. When lava flows through forests, it instantly ignites everything in its path. Because lava is so hot, it doesn’t need dry vegetation to spread fire. It simply burns anything it touches. 

Spontaneous Combustion

Wildfires can sometimes start without external ignition. Decomposing organic material, like dry leaves or compost piles, can generate heat as they break down. If the heat builds up enough, it can ignite the surrounding material and lead to a wildfire. While this is less common than other causes, it’s still something to be aware of in dry, hot conditions.

Climate Change

Rising global temperatures and longer droughts make wildfires more frequent and intense. Drier vegetation means there’s more fuel for fires to burn. Scientists estimate that for every one-degree Celsius increase in temperature, lightning strikes increase by 12%. More lightning means more fires. For example, hot and dry conditions in 2021 led to 65% more dry vegetation in California. That’s a recipe for disaster where a small spark can start a wildfire.

How Do Wildfires Spread?

Wildfires spread based on three main factors: fuel, weather, and topography. 

Fuel is anything that can burn, like dry grass, dead leaves, or trees. The drier the fuel, the faster the fire spreads. Small fuels like grass ignite quickly but burn out fast. Large fuels, like tree trunks, take longer to catch fire but burn hotter and longer. Some plants even have oils that make them extra flammable.

Weather plays a big role, too. Wind speeds up fires by pushing flames forward and carrying embers to new areas. High temperatures and low humidity dry out fuel, so it’s easier to ignite. That’s why wildfires usually get worse in the afternoon when it's hottest. On the other hand, rain can slow or stop a fire.

Then there's topography or the shape of the land. Fires move faster uphill because heat rises and preheats the fuel above. South-facing slopes dry out quicker since they get more sun, making them more fire-prone.

While we can control some of these factors (like managing fuel and preventing sparks), others (like wind and oxygen) are beyond our control. For these reasons, wildfires are unpredictable.

How Fast Do Wildfires Spread?

Wildfires can spread at different speeds depending on wind, terrain, and fuel. On average, wildfires move between six to 14 miles per hour. However, they can race as fast as 60 miles per hour under extreme conditions.

How Long Do Wildfires Last?

How long a wildfire lasts depends on fuel, weather, and terrain. Some fires burn out in a day or two, while others rage for weeks or months.

Strong winds, dry vegetation, and drought conditions prolong wildfires. In places like California, the Santa Ana winds can keep fires burning until conditions change. If rain comes or winds calm down, fires slow or stop. Natural barriers, like rivers or rocky terrain, can also help.

However, climate change makes wildfires last longer. Warmer temperatures and less rain mean drier landscapes. These create perfect conditions for wildfires to keep burning. Decades ago, wildfires lasted around eight days on average. Now, they can burn for over a month. In addition, the fire season used to be about five months long. Now, it lasts for seven months. As temperatures keep rising, wildfires get harder to control, burn more land, and last longer.

Where Do Wildfires Occur?

Wildfires can happen almost anywhere, but they’re most common in places with dry weather, lots of vegetation, and wildfire history. Some regions are especially prone to them.

In the Western United States, states like California, Oregon, and Arizona deal with wildfires every year. Dry summers, strong winds, and flammable vegetation make these areas high-risk. Australia is also no stranger to wildfires, or bushfires, as they call them. Hot summers and dry landscapes lead to massive fires, especially in the southern and eastern parts of the country.

In Southern Europe, countries like Spain, Portugal, Italy, and Greece regularly face wildfires. Their Mediterranean climate means hot, dry summers—perfect conditions for fires to spread. The Amazon Rainforest in South America also experiences wildfires, though many are caused by deforestation and land clearing instead of natural causes.

Even Siberia and parts of Russia experience large-scale wildfires during the summer when forests dry out. In Southeast Asia, places like Indonesia, Malaysia, and Thailand often deal with fires linked to land-clearing practices like slash-and-burn agriculture.

Wildfires don’t just burn in forests. They can occur in grasslands, shrublands, and savannas, too. Some fires burn just above the ground, while others ignite deep underground and smolder for months. In places like California’s Sierra Nevada, fires can burn at different levels―on the surface and in tree canopies.

Overall, wildfires are a global issue. Climate change makes them worse, with longer dry seasons and rising temperatures creating the perfect conditions for more frequent and intense fires.

When Is Wildfire Season?

In the past, most wildfires in the US happened between June and September, when the weather was hottest. But in recent years, the fire season has stretched beyond that. Some experts now consider it a year-round problem, especially in Southern California.

Wildfires have become more destructive since 2000. They’ve burned twice as much land as they did in the 1990s. With rising temperatures and prolonged droughts, the wildfire season isn’t just getting longer. It’s also becoming more dangerous.

How to Protect Your Loved Ones From Wildfires

Wildfires spread fast, but a little preparation can make a big difference. Knowing the risks, maintaining your yard, and having an evacuation plan help protect your home and family. Here’s how to stay ready and keep your loved ones safe: 

1. Stay Informed

Wildfire risks change depending on the weather, drought conditions, and fuel availability. Stay updated by checking local fire risk levels (like red flag fire weather warnings) and learning about potential dangers, especially if you live near forests or grasslands.

2. Keep a Fire Prevention Kit

Keep a fire prevention kit with essentials like a fire blanket, fire spray, fire protection gloves,  fire extinguisher, and hose long enough to reach all areas of your home. These tools can help you respond quickly if a fire starts.

3. Maintain Your Yard

Remove dry leaves, dead branches, and other flammable materials from your yard, roof, and gutters. Trim overgrown vegetation and space out trees to prevent fire from spreading. Use lawn equipment cautiously, especially during hot, dry, or windy conditions.

You should also have up to 100 feet of defensible space around your home, with the first five feet free of flammable materials. Use fire-resistant materials for roofs, siding, and decks to slow fire spread.

4. Use Fire Responsibly

Build campfires in a safe, open location. Keep them small, and fully extinguish them before leaving. Keep grills away from dry grass and properly dispose of coals. If you’re using fireworks, do so in a safe area and have water nearby. Plus, make sure the fire is completely out before you throw away cigarette butts. 

5. Be Ready to Evacuate

Pack an emergency kit with important documents, medications, and other essentials. Check out how to build a go bag or family bug out bag here. Have a family evacuation plan as well. If authorities tell you to evacuate, do so immediately.

Conclusion

Wildfires are a growing problem, and understanding how they start helps prevent them. While we can’t control lightning or the wind, we can be more responsible with campfires, yard work, and home fire safety. Simple steps like clearing dry leaves, checking weather conditions, and following fire regulations make a big difference. Staying prepared helps protect homes, communities, and the environment.