It is not possible for fire to be cold, although fire can be cool.
Cool flames of a fire can occur in hydrocarbons, oils, acids, aldehydes, waxes and methane.
The lowest temperature of a cool flame is poorly defined though and is also conventionally set as a temperature at which the flame can be detected by eye in a dark room.
Cool flames are barely visible in daylight.
At temperatures as low as 248 F, fuel-air mixtures can react chemically and produce very weak flames that are called cool flames which is a phenomenon that was discovered in 1817 by Humphry Davy.
The science behind starting a fire is a chemical process called combustion, which is a rapid reaction that occurs between a fuel and an oxidant which is typically oxygen to produce heat, light and various byproducts.
Fire science is focused on the Fire Triangle, which states that 3 elements are necessary for a fire to occur, which include oxygen, fuel and heat.
Heat is what provides the initial energy needed to raise the fuel to it's ignition point.
Fuel is any material that can burn, like wood, flammable liquids or paper etc.
Oxygen is what acts as the oxidizing agent to react with the fuel to start the fire.
Another science behind starting a fire is the concept of Fire Tetrahedron, which adds a 4th element, which is the chemical chain reaction.
The chemical chain reaction is a self sustaining process in which heat from the initial ignition breaks down fuel molecules and releases reactive particles that are called free radicals which further react with oxygen and creates more heat and perpetuating the fire.
other things that are involved in starting a fire are the Ignition temperature, the process of ignition, role of oxygen and the stages of a fire.
For the process of ignition and to start the fire, you have to provide sufficient heat to raise the fuel to it's ignition temperature in the presence of oxygen.
The heat source to start the fire can be anything from a spark such as from a flint and steel or friction or open flame.
After the fire is ignited, then the chemical chain reaction takes over and releases heat and allows the fire to sustain itself.
The role of oxygen is important for starting a fire and sustaining it as well as oxygen is crucial for combustion to occur as it acts as the oxidizer which reacts with the fuel.
Increased oxygen levels can also lead to more intense and faster fires.
And restricting oxygen supply such as by smothering a fire with a fire blanket can extinguish the fire.
There are also 4 stages that fire goes through which include.
The incipient stage which is the initial phase of ignition that is often characterized by smoldering or a small flame.
The growth stage which is the stage that the fire increases in size and intensity as it consumes more fuel and oxygen.
The fully developed stage in which the fire reaches it's peak intensity, burning all available fuel and oxygen.
And the decay stage which is when the fire decreases in intensity as the fuel supply for the fire runs out.