Wildfire glossary
Plain-language definitions of the wildfire terms used on this map: satellite hotspot, FRP intensity, fire weather index, confirmed fire, burnt area and more.
- Satellite hotspot
- A point where a satellite sensor (VIIRS or MODIS) detected strong heat. Most are wildfires, but some are industrial heat, gas flares or agricultural burning. A hotspot is a detection, not a confirmed fire.
- Fire Radiative Power (FRP)
- How much heat a fire is giving off at the moment of detection, in megawatts (MW). Higher FRP means a more intense fire. We use it to shade fires by intensity.
- Fire event
- A group of nearby detections of the same fire, merged into one event with its own page, so repeated passes over one fire are not counted as many fires.
- Confirmed vs possible fire
- A fire is "confirmed" when it matches an official incident or repeated, intense detections. A "possible" fire is a single unverified detection that may be another heat source.
- Fire Weather Index (fire danger)
- A 0–5 scale (Very low to Extreme) modelled from temperature, humidity and wind that describes how easily fires start and spread today — not whether a fire is currently burning.
- Burnt area / perimeter
- The ground area a fire has burned, drawn as a polygon. Where an official agency publishes perimeters, we show them; otherwise the map shows satellite hotspots only.
- VIIRS & MODIS
- The two NASA/NOAA satellite instruments behind the detections. VIIRS is higher resolution (375 m); MODIS is older (1 km) but adds passes.
- Active fire
- A fire with recent satellite detections or an open official incident. The active list drops fires once detections stop or the incident is closed.