How fast is a dangerous rate of spread?

How fast is a dangerous rate of spread?

• A. Up to 1 mph
• B. More than 3 mph
• C. 0 mph
• D. 1-3 mph

Answer: (D)

Rate of spread is how fast the fire front moves across the landscape. A dangerous rate of spread is defined in this material as one to three miles per hour. This speed is fast enough to threaten crews and complicate suppression efforts—giving little time to react if conditions shift—without being at the extreme end where conditions are dramatically more dangerous. A rate of spread slower than that (up to one mph or less) is less risky, while a rate over three mph signals very severe fire behavior that requires immediate, heightened response. So, the 1–3 mph range best matches the stated threshold for a dangerous rate of spread.

Rate of spread is how fast the fire front moves across the landscape. A dangerous rate of spread is defined in this material as one to three miles per hour. This speed is fast enough to threaten crews and complicate suppression efforts—giving little time to react if conditions shift—without being at the extreme end where conditions are dramatically more dangerous. A rate of spread slower than that (up to one mph or less) is less risky, while a rate over three mph signals very severe fire behavior that requires immediate, heightened response. So, the 1–3 mph range best matches the stated threshold for a dangerous rate of spread.