Can it be too cold to start a fire? Can extreme cold put out a fire? In both cases, the short answer is yes. Here’s the explanation.
Can It Be too Cold to Start a Fire?
The reason it can be too cold to start a fire is because fire needs three or four things to exist. In the fire triangle, fire needs oxygen, heat, and fuel to support combustion. The heat you use for starting a fire gives combustion the activation energy it needs to get started. Once a fire gets going, it still needs that activation energy, but it usually gives out enough heat to sustain a chain reaction (the additional element in the fire tetrahedron).
But, there is no single temperature that is too cold for fire. Each fuel has its own ignition temperature. So, a temperature that is too cold for one type of fire may be perfectly fine for another fuel. Another factor that affects the ignition temperature is the particle size of the fuel. Combustion starts more easily when the fuel has a lot of surface area. For example, finely powdered sawdust ignites more easily than a log.
What About Cold Weather?
Cold weather can either aid or deter fire-starting, depending on several factors. For example, a cold front typically carries moisture and has wind. Wind increases the supply of oxygen to a fire and carries away combustion products. But, too much wind carries away the heat from an ignition source. A dry wind helps remove moisture from a fuel, while precipitation hinders fire-starting because water has a high heat capacity and reduces the effect of the ignition source. The main reason starting a fire is harder in cold weather is because everything is more complicated when you’re all bundled up with gloves or else have cold hands.
Very rarely does the temperature get cold enough that the fuel won’t catch. However, once the temperature dips to -40 °F or °C, some common fuels freeze and get much harder to ignite. This is because combustion is a chemical reaction between gas molecules. Below -45°F, gasoline doesn’t have a high enough vapor pressure for ignition. The resulting fire has to maintain a temperature of at least 536°F for a chain reaction.
Can Cold Put Out a Fire?
Cold can put out a fire because fire needs a certain threshold of energy for supporting a chain reaction. Once again, there is no set temperature where this occurs. One reason water puts out many fires is because it absorbs heat, not so much because it smothers the flame.
Yet, combustion occurs even in the cold of space. Cold doesn’t extinguish rockets because the fuel and oxidizer aren’t at absolute zero. Because the chemicals consist of matter, they aren’t a vacuum. The Sun and other energy sources heat the rocket engine, plus combustion keeps the reaction hot enough for a chain reaction. In cases where freezing fuel is a concern, heaters keep it at the appropriate temperature. However, usually cooling is the bigger concern.
References
- Fire Safety Advice Centre (2021). Information about the Fire Triangle/Tetrahedron and Combustion.
- IFSTA (2019). Essentials of Firefighting (7th ed.) ISBN: 978-0-87939-657-2.
- Moritz, Max A.; Morais, Marco E.; Summerell, Lora A.; Carlson, J. M.; Doyle, John (2005-12-13). “Wildfires, complexity, and highly optimized tolerance”. Proceedings of the National Academy of Sciences of the United States of America. 102 (50): 17912–17917. doi:10.1073/pnas.0508985102