The Watch Duty fire perimeter layer is sourced from the National Interagency Fire Center (NIFC), FIRIS, and various other government sources. These are all official perimeters and Watch Duty does not make our own perimeters for a fire.If a fire perimeter isn't available, it often hasn't been mapped yet.

Thanks to the FIRIS program, California fires are frequently mapped in their early stages. In areas outside of California, fires are generally infrared-mapped overnight, and these are included in Watch Duty in the morning.

Our Satellite Hotspot layers are also good indicators of where the fire is currently, if available. These are heat signatures that can often detect routine operations at landfills and other industrial facilities. On wildfires, they generally indicate where the fire is, but by no means do they indicate that everything within the hotspot is involved in fire.