Wildfires aren’t easy to control to begin with. Throw in some strong winds and dry air and you’re in for a tough clean-up job. However, fighting wildfires in poor weather conditions isn’t impossible. You simply have to know how the weather affects the spread of wildfires, and you’ll have a better understanding of how to control them.
On the other hand, optimal weather conditions can prevent wildfires from igniting or spreading, so weather can be either a blessing or a curse. It’s important for both firefighters and the Average Joe to understand wildfire risks to ensure everyone’s safety. Take a look at the following weather conditions that affect wildfire suppression to learn more.
Three Major Factors of Wildfire Development
There are three main weather-related factors that affect wildfires. We take a look at each below.
Fires require three ingredients:
Because heat is needed to complete the “fire triangle,” wildfires are more likely to break out in hot seasons or climates.
Human error is the number one cause of wildfires. As many as 90 percent of wildfires in the United States are started this way, for instance by a discarded cigarette or an unattended campfire.
Once that fire has been lit, it’s much more likely to spread when the air is hot. That’s because in hot weather, the sun is typically more intense, which heats and dries out fuels such as sticks and other flammable debris.
That’s why wildfires most commonly spread fastest in the afternoon when the air is hottest.
Like temperature, humidity is a strong predictor of how fast a wildfire will spread. Fires grow much more quickly in drought conditions because fuel such as dry leaves and sticks can catch fire easier and burn faster.
On the other hand, humid climates are less likely to see fires catch, and if they do, they don’t spread as fast. That’s because the fuel itself contains more water, which helps absorb some of the fire’s heat.
In areas of high moisture and plenty of precipitation, rain can suppress the chance of fires even breaking out since the fuel is hard to ignite.
While wildfires spread quickest in hot, dry areas, the real predictor of a fire’s behavior is wind. Unfortunately, wind patterns can also be highly unpredictable. Wind typically affects fires in these ways:
- Fires will follow the direction the wind blows.
- The faster the wind is blowing, the faster the fire spreads.
- The wind can blow around embers, which can ignite other areas and spread the fire faster.
- Wind gusts can elevate the fire into the trees.
- Wind can change the direction of the fire, which makes predicting and fighting it tough.
It’s not just the wind patterns of the area you have to pay attention to, either. Wildfires themselves can create their own wind patterns, which also affects how the fire spreads. In extreme cases, fires can create their own swirling whirlwinds from their heat, which again will contribute into how fast and dangerously the fire spreads. In some cases, a fire’s own winds can blow 10 times faster than the air around them.
Other Factors That Affect Fires
Now that you understand the three major weather factors that can lead wildfires to grow out of control, let’s take a look at a few examples of other weather patterns that can affect wildfires.
A cold front can both encourage fire growth and suppress it. Cold fronts are masses of advancing cold air. Typically, the air is also moist. When a cold front moves in, that means the air will chill and contain more moisture, two factors that can suppress a fire and keep its spread at bay.
However, cold fronts typically come with strong winds as well, which can stir up a fire and provide it with more oxygen to burn more intensely. Because of that, cold fronts have been known to reignite dying fires and, in some cases, change the fire’s direction.
Humans are not the only cause of wildfires. Lightning is also a common culprit. When thunder and lightning storms are dry (without rain), the chances of igniting a wildfire are even higher since there’s little humidity to slow its spread.
On the other hand, a wet thunderstorm with sufficient rains can provide fire relief or reduce the risk of a fire lighting.
Why This Knowledge is Useful
Through much research, scientists and firefighters have come to understand what types of weather patterns can affect the ignition and spread of wildfires. They’ve even discovered that fires themselves can adopt their own weather patterns and affect the weather of the surrounding area. But how does any of this help us?
For one, understanding how weather affects fires can help firefighters predict how to cut off a fire from spreading, where to attack the fire, and how to put it out. Although some factors can be quite unpredictable — such as changes in wind direction and speed — there is still merit in understanding the relationship between weather and fires. In fact, scientists have used this knowledge to develop computer models that can predict how a wildfire will grow and spread.
Being able to predict the chance of a fire is also useful to authorities as they can send out alerts during hot, dry days. At times, fire regulations may be put into place to prevent fires from ever starting. For instance, if fire danger is high, campers will be prohibited from lighting camp fires until the danger has subsided. This ensures citizen safety and reduces the need for extra resources for fighting potential fires. The fewer fires that break out, the better!
Whether you want to be a wildland firefighter someday or you’re just interested in staying safe in dry climates, understanding how the weather can impact a fire’s danger is important. Since fires can be unpredictable thanks to the weather, stay safe by complying with fire regulations and, if you choose to fight fires, always follow safety procedures. Keep these factors in mind if you ever encounter a wildfire.