Brrr. Can you feel that chill in the air? The temperatures are very cold right now. The weather might not be fit for man nor beast, but your local fire department must still respond to calls. Does the cold weather affect how fast a fire can spread? Can cold even put out a fire?
Cold air as generated by cold fronts might stop or limit a fire if the temperatures are cold enough and the air has a certain amount of moisture. However, if cold weather is accompanied by high winds, the winds can feed fire oxygen and encourage its spread.
In this article, we’ll talk in a lot more detail about the influence cold weather has on fires, both good and bad. We’ll even discuss if cold air alone can extinguish fire, so make sure you keep reading!
The Effects of Cold on Fires
When a wildfire breaks out, its size and spread are influenced by three factors. These are wind, humidity, and temperature.
Keeping that in mind, let’s examine what a cold front does to an ongoing fire.
A cold front is defined as a weather event in which cold air advances on a warm low-pressure system’s trailing edges. From the ground level, the warm air is pushed out by the colder air. The temperatures begin to go down, often drastically, and the wind will pick up.
Cold fronts, despite the name, do not always lead to snow events. Rather, the most frequent weather patterns following a cold front are lightning, thunder, and rain with maybe some hail. For snow to occur, you’d need precipitation, then a warm front, which might advance to either snow or rain depending on the temperature.
On top of that, cold fronts aren’t exclusive to the winter, either. If you’ve ever had a summer day that started warm and got quite a lot chillier, and then later a storm occurred, that’s a cold front.
A cold front, while not delivering snow and not occurring solely in winter, does indeed bring with it cooler conditions. Can the cold put out the fire?
With a cold front usually comes an uptick in wind. If a fire had started and mostly petered out, any remaining embers could be reignited by the wind caused by the cold front. The fire would then start up again.
If a fire hadn’t begun, the strong winds could ignite it and sometimes even alter its direction.
However, cold fronts are usually moist. It’s humidity’s moisture that makes it adept at stomping out fires, so thus, a cold front’s moisture levels are efficient for doing the same. The colder temperatures rolling through also don’t accelerate a fire.
Therefore, cold fronts can cause fire events and strengthen them, but not to the same degree as warmer weather could.
Can Cold Air Put Out a Fire?
According to the National Fire Protection Association or NFPA, between 2015 and 2019, 26 percent of fires reported were indoors. We can assume then that the remaining 74 percent occurred outdoors.
Let’s say a fire took place in freezing weather. Freezing temperatures are those that are under 32 degrees Fahrenheit, which is the freezing point of water. Could the temperatures get so cold that the fire stops burning?
While that would be nice, it’s not exactly what happens.
How do we know? Well, in February 2015, a fire broke out in West Philadelphia, Pennsylvania at a commercial building. When firefighters arrived on the scene and used their hoses to combat the blaze, something fascinating did occur.
According to news resource The Morning Call, when the firefighters began blasting at the fire with their highly-pressurized hose water, the water froze on the spot. That’s certainly something right?
The firefighters did eventually combat the blaze, but it took about three hours to control it. Considering the building was two stories as well as the interesting circumstances the firefighters were up against, that’s not bad!
The fire did indeed continue to burn even though the temperatures were well under freezing. That answers the question then. Firefighters, or anyone really, cannot put out a fire with cold.
Other Weather Conditions and Their Influence on Fire
Now that we’re certain that cold cannot put out a fire, we thought we’d take this section to discuss the effects of weather on fire.
Before we delve into it, remember that fire needs three things to burn, and they are heat, oxygen, and fuel. Together, they form the fire triangle.
Think of the fire triangle as a chair that can miraculously stand on three legs. Once you take one of those legs out, and especially if you take two out, the chair (fire) can’t stand (burn).
As established earlier, cold fronts can lead to thunderstorms. Warm fronts can cause thunder as well due to instability in the air. A warm front sends warm air in the way of cold air, and that’s when the storms usually develop.
Thunderstorms deliver rain, thunder, and lightning. The latter especially is dangerous, as a lightning strike can cause ground-level objects to burst into flame depending on what those objects are.
It’s often trees that burn from a lightning strike, but not all trees will ignite. Trees have water within their cells deep below the bark. When struck, the water rapidly warms and begins boiling. This is why a tree might look like it’s giving off steam; that’s exactly what’s happening.
If the tree doesn’t burn, then its trunk will be charred or blackened, but otherwise, the tree will be no worse for wear. A tree that does burn is a hazard to anything around it, as flammable objects will get caught in the blaze, allowing the fire to spread.
Lightning can strike a power line and down the line or even cause a transformer to explode. Both these events can cause a fire as well.
Even outside of the extreme damage that lightning can cause, thunderstorms can still contribute to fires in other ways. Dry storms have little humidity, which can encourage the start of a wildfire. If the dry storm is accompanied by high winds, then the risk of a fire is even higher.
If a thunderstorm leads to soaking rains though, the extra moisture will make it more difficult for fire to occur. Difficult does not mean impossible though!
Wind gusts are one of the biggest contributors to fire. You may recall that wind can reignite a dying fire and allow it to spread or accelerate the beginnings of a new fire.
Depending on the wind direction, gusts can change the direction of a burning fire in kind. This makes the duties of a firefighter harder as they have to predict how the fire may spread.
Wind can also send fire up, such as into a tree. If the fire didn’t affect the tree before, it would now.
The last weather factor that can influence fire is humidity.
You often hear of wildfires during drought conditions, such as in California. This is not a coincidence. Droughts prevent rain, and rain provides moisture that can stop fires or limit the spread. When an area is dry, trees are likelier to burn, and the wildfire can quickly engulf entire small cities and towns.
Humid regions don’t have fires nearly as often since they have the protection of moisture in the air. Objects that can catch fire in drier environments cannot do so nearly as easily in a humid one. If a fire does start, its spread is often limited, which makes the fire manageable for a quick-responding fire department.
We must note that heat and humidity are not the same thing. Heat refers to the temperature while humidity is a measure of moisture in the air. Humidity can make hot temperatures feel even hotter, but it’s just how sticky and wet the air is. It has nothing to do with temperature.
Cold alone cannot stop nor put out fire. If that was the case, then places like Alaska would never have fires. The Wildfire Smoke Prediction for Alaska website shows us that’s not true.
Although cold fronts don’t impede the development of fires, the weather still plays a huge role in how large fires can get and how much they will spread. A lack of humidity combined with strong winds and high temperatures accelerates fire. Mild winds, cold temperatures, and moist conditions decelerate fire.