Wind speeds and live fuel moisture level are the critical measures of fire risk in chaparral. Fuel moisture levels have been approaching critical this season in Southern California and, due to lack of rain, didn't follow the seasonal pattern:
https://fire.lacounty.gov/wp-content/uploads/2024/11/All-Are...
Some relevant research: https://moritzfirelab.org/wp-content/uploads/2016/01/denniso...
Drought is a more comprehensive measure that includes snowpack, rainfall, resevoir levels, etc.