Weather and Fuel Conditions

Prescribed Fire Plans identify weather and fuel conditions appropriate for conducting prescribed fire. These conditions are a balance of the fire behavior need to meet objectives and the ability for holding resources to control the fire. Fire behavior modeling programs are used to identify the weather and fuel conditions that produce the fire behavior necessary to meet those conditions. Weather and fuel parameters that are given additional consideration include:

Wind: In the boreal forest systems most large fires are a result of high wind conditions. Eye level wind speeds in excess of 25 miles per hour have been found to be problematic at times. Therefore, when planning a prescribed burn wind conditions are continually monitored.

Drought: The other variable that has been present during large fire events in boreal system is dry fuel conditions. Prolonged lack of moisture produces drought conditions which results in dry fuel conditions. Drought codes are monitored to ensure fuel conditions are not too dry. For more information on drought indices see: The Canadian Fire Behavior Prediction System is used to monitor drought conditions on the Superior National Forest. For more information on this see:

There are a limited number of days each year that meet the conditions appropriate to conduct prescribed burning. On a give year there are 10-20 days which prescribed fire can be conducted.

Typically, prescribed fire conditions are most appropriate in early spring and fall. In early spring, fuel conditions are drier because vegetation is coming out of dormancy. Once green-up occurs, vegetation is at full water content and holds moistures making it difficult to burn. In the fall, vegetation is beginning to go into dormancy and water content is beginning to drop off. Also in the fall time, the shorter days create condition which do not support high intensity fire or prolonged burning which can be problematic from a control stand point.