- Spread Component – A rating of the forward rate of spread at the head of a fire.
- Energy Release Component – A number related to the available energy (BTU’s per square foot within the flaming front at the head of a fire.
- Burning Index – A number related to the contribution of fire behavior to the effort of containing a fire.
- Ignition Component – A rating of the probability that a firebrand will cause a fire requiring suppression action.
- Keetch-Bryam Drought Index – A number (0-800) defining how may hundredths of an inch of water is required to saturate the soil. This index was not part of the original NFDRS, but was added in a 1988 revision.