Data Sources

NASA FIRMS — Fire Detection Data

Active fire detections on this site come from NASA FIRMS (Fire Information for Resource Management System), operated by NASA's Earth Science Data and Information System (ESDIS) project. FIRMS aggregates near-real-time active fire data from multiple satellite instruments.

How NASA Satellites Detect Fires

Satellites detect fires using thermal infrared bands that can identify anomalous heat signatures on the Earth's surface. Two primary instruments are used:

• MODIS (Moderate Resolution Imaging Spectroradiometer) — aboard the Terra (EOS AM-1) and Aqua (EOS PM-1) satellites. MODIS detects fires at 1km pixel resolution and passes over most of the Earth approximately twice per day per satellite (four times combined). It uses the 4-micron thermal band (band 21/22) to identify hotspots significantly above background temperature.
• VIIRS (Visible Infrared Imaging Radiometer Suite) — aboard the Suomi NPP and NOAA-20 satellites. VIIRS offers higher spatial resolution (375m pixels) compared to MODIS, reducing omission errors for small fires. VIIRS uses the I4 and I5 bands (3.7 and 11 microns) for fire detection.

What "Confidence" Means

Each FIRMS detection includes a confidence level: high, nominal, or low. This is calculated from multiple factors including the brightness temperature, the contrast with surrounding pixels, the time of day, and the surface type. High-confidence detections are very likely to be active fires. Low-confidence detections may include false alarms from sun glint, industrial heat, or geothermal activity. On the map, we display all detections but use color to indicate confidence level (red = high, orange = nominal, yellow = low).

What FRP (Fire Radiative Power) Measures

Fire Radiative Power (FRP) is expressed in megawatts (MW) and represents the rate at which a fire is releasing radiative energy. It is directly proportional to the rate at which biomass is being consumed. Higher FRP indicates a more intense fire. FRP values of 10–50 MW are typical for moderate fires; values above 500 MW indicate extreme fire behavior. FRP is a key input for smoke emissions modeling and air quality forecasting.

Source: firms.modaps.eosdis.nasa.gov. API key: FIRMS_MAP_KEY (free registration).

NIFC — National Interagency Fire Center

Named fire incident data comes from the National Interagency Fire Center (NIFC), which coordinates federal wildland fire management across multiple agencies including the USDA Forest Service, Bureau of Land Management, Bureau of Indian Affairs, National Park Service, US Fish & Wildlife Service, and state forestry agencies.

How NIFC Tracks Named Fires

When a wildland fire is large enough to require coordination across multiple agencies or jurisdictions, it is assigned an official incident name. Incident data is recorded in the IRWIN (Integrated Reporting of Wildland-Fire Information) system, which provides a single source of truth for fire name, location, acreage, containment status, cause, and suppression resource data.

What Containment Percentage Means

"Containment" does not mean the fire is out. A fire is considered contained when a control line (fireline) has been built completely around the fire perimeter. The containment percentage represents the fraction of the total fire perimeter that has a completed control line. A fire at 100% containment may still have active burning inside the perimeter — it is simply no longer expected to spread further. "Controlled" means all burning within the perimeter has ceased. "Out" means no heat remains detectable.

Source: nifc.gov. Data is publicly available with no registration required.

Wildfire Smoke and Health Risk

Wildfire smoke is a complex mixture of gases and fine particles. The primary health concern is PM2.5 — fine particulate matter with diameter less than 2.5 micrometers. At high concentrations, PM2.5 can penetrate deep into the lungs and enter the bloodstream.

The EPA's Air Quality Index (AQI) is the standard measure. At AQI > 100 (Unhealthy for Sensitive Groups), people with heart/lung disease, older adults, and children should reduce prolonged outdoor exertion. At AQI > 150 (Unhealthy), everyone should limit outdoor exertion. At AQI > 200 (Very Unhealthy), everyone should avoid prolonged outdoor activity. At AQI > 300 (Hazardous), emergency conditions — everyone should stay indoors with filtered air.

Fire FRP and distance from detection are rough proxies for smoke impact, but actual smoke concentration depends heavily on wind direction, atmospheric mixing height, and terrain. For current AQI data, check AirNow.gov.