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The Increasing Risk and Intensity of Wildfires

As more people move into areas that are close to wild, natural landscapes, like forests and grasslands, there’s a higher risk of wildfires. This is because human activity in these areas can accidentally start fires. Currently, around 45 million homes are in or near wild areas, with 72,000 communities at risk from wildfires. This phenomenon is known as the wildland-urban interface (WUI).

Because the WUI is expanding and wildfires are getting bigger and more intense, it’s becoming difficult for firefighting organizations to protect every home in danger. This makes it crucial for residents to understand their wildfire risk and prepare themselves to stay safe during wildfires.

At the same time, it’s been getting hotter and drier in areas where people live close to natural places, like forests and woods. This makes wildfires happen more often, and they become larger and more dangerous. Pine tree areas are especially tricky because the fires there burn hotter, spread high up in the trees, and are tough to stop. They also create large smoke clouds that can go very high and carry embers that start new fires as they fall.

On this page you will find How Wildfires Ignite Structures and Assessing Your Regional Area Wildfire Risk.

How Wildfires Ignite Structures

There are 3 ways in which structures ignite from wildfires. These include:

Direct Flame Contact: When a wildfire’s flames directly touch a building, they can swiftly set fire to anything that can burn, like wooden walls, roofs, decks, or nearby plants. The intense heat can cause rapid spreading of the flames within the structure.

Radiant Heat: Radiant heat, which moves as infrared radiation, can set fire to things like wood, dry plants, or flammable siding on buildings. It can cause ignition even if flames don’t make direct contact with the structure.

Embers: Embers, also called firebrands, are fiery bits of debris carried by the wind during a wildfire. They can travel quite a distance ahead of the main fire and land on buildings or the surroundings. If these embers land on or get stuck between things that can burn, like dry plants, wood, or flammable debris, they can start new fires. Embers can even get inside homes through openings like vents, windows, or doors, or ignite things stored close to buildings.

During wildfires, almost 90% of buildings catch fire when the wind carries embers onto the building or other nearby flammable objects like fences, decks, or wood piles. When a building catches fire, the flames can quickly spread from one part to another or even to nearby buildings, making the fire worse. This is called “structure-to-structure fire spread.” It’s important to know how this happens when you’re figuring out how to protect your property from wildfires. Click here for a demonstration of how embers affect buildings.

Assessing Your Regional Area Wildfire Risk

Multiple factors affect the likelihood and intensity of wildfires. Some of these factors include:

Flammable Vegetation: The number of plants, like grass, bushes, trees, and pine trees, in the area around your property can make wildfires more likely and make them spread faster.

Land Shape and Steepness: If the land around your property is very steep, it can make wildfires move faster and make it harder for firefighters to control them.

Seasonal Weather Conditions: The temperature, humidity, and wind speeds during different seasons, affects how likely wildfires are to start and how quickly they can spread. When it’s hotter, drier, and moderately windy, the risk of wildfires goes up.

Rainfall: In places where it doesn’t rain much, especially in lower areas, the risk of wildfires is higher.

Past Wildfires: Looking at how often and how big wildfires have been in the area over the past ten years can help figure out how risky the area is for wildfires. Large past wildfires mean a higher risk.

By looking at these factors, you can understand and decide how much of a risk your property might have from wildfires.

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