Table 1. Climate metrics used to predict the natural logarithm of annual area burned.
| Category | Predictor metric(s) | Response time | Temporal resolution | Opt. time window |
|---|---|---|---|---|
| Fire-danger metrics | Fine-fuel moisture code (FFMC) | < 1 day | daily | 90-day max. |
| Duff moisture code (DMC) | 15 days | daily | 90-days, 1 Sep. | |
| Drought code (DC) | 52 days | daily | 1 day, 1 Sep. | |
| 100-hr fuel moisture (FM100) | 5 days | daily | 105-day min. | |
| 1000-hr fuel moisture (FM100) | 42 days | daily | 60-day min. | |
| Burning index (BI) | 30+ days | daily | 90-day max. | |
| Energy release component (ERC) | 30+ days | daily | 90-days, 15 Sep. | |
| Water-balance metrics | Soil moisture (SM) | > 30 days | daily | 30-day min. |
| Potential evapotranspiration (PET) | daily | monthly | June-August tot. | |
| Weather / climate metrics | Temperature (T) | NA | monthly | July-August mean |
| Precipitation (P) | NA | monthly | June-August tot. | |
| Standardized precip. index (SPI) | NA | three months | August | |
| Jan.-October growing-degree days (GDD0) | NA | monthly | Jan.–Oct. (forced) |
The “optimal time window” defines the within-year period over which each metric is summed or averaged; see “Materials and Methods” for details.