Flashover

Flashover is a rapid, intense stage in a fire’s development where the heat causes combustible gases and surfaces within a room to reach their ignition temperature simultaneously. This leads to a sudden, almost explosive spread of flames across the entire space, turning a localized fire into a full-room or full-structure blaze. It occurs when the room’s temperature becomes extremely high—often over 1,000°F (538°C)—and is a critical point for firefighters to understand because it signals that the fire has reached its most dangerous phase, requiring immediate action to ensure safety.