A weather-driven wildfire occurs when atmospheric conditions are the dominant factor in fire spread. So-called "sixth-generation fires" are characterised by creating their own weather: pyrocumulonimbus, fire tornadoes, and convective columns that modify wind patterns.
Risk indices
Weather services calculate indices like Canada's FWI (Fire Weather Index) combining temperature, humidity, wind, and accumulated drought. In Spain, AEMET publishes a daily risk index. Santa Ana winds (California), tramontana, and cierzo (Spain) are winds associated with the worst fires due to their dry gusts.