Which condition is indicative of a flashover during a fire?

A rapid increase in smoke and heat is a critical indicator of flashover during a fire. Flashover occurs when the temperature in an enclosed space rises sharply, causing combustible materials to ignite almost simultaneously. This phenomenon happens when all exposed surfaces reach their ignition temperature, leading to a violent and transformative stage in the fire's growth.

The rapid increase in smoke is a sign that the fire is reaching this critical point, as smoke production increases significantly due to the combustion of materials within the environment. Notably, the heat generated during this phase may become unbearable, indicating that a flashover is imminent. Understanding this condition is vital for firefighters, as it assists them in recognizing when an environment has become extremely dangerous and when immediate action or evacuation may be necessary.