Map Guide — Legend & Layers

This guide explains the symbols, thresholds, colors, and data sources used in FEAST map layers: PM2.5, Ozone, Rx Size, Wildfires, and HMS Fire & Smoke. It also includes tips for turning layers on/off and exploring time ranges.

Fine particulate matter (PM2.5) ≤ 2.5 µm, measured by the AirNow and AQMIS Network. Color-coding uses the daily (24-hour) standard: 35 µg/m³. FEAST shows California monitoring sites.

Data source: AirNow
Data source: AQMIS
  • Green: PM2.5 < 35
  • Red: PM2.5 ≥ 35

Maximum 8-hour ozone concentration from AirNow and AQMIS. Threshold based on EPA standard: 70 ppb. FEAST shows California monitoring sites.

Data source: AirNow
Data source: AQMIS
  • Blue diamond: O3 < 70
  • Red diamond: O3 ≥ 70

Prescribed fire burn size as reported by burners, color-coded with a threshold of 50 acres. PFIRS is a California system; FEAST displays California burns.

Data source: Prescribed Fire Information Reporting System (PFIRS)
  • < 50 acres
  • ≥ 50 acres

Real-time wildfire information is obtained from CAL FIRE incident data, which provides point locations and reported fire sizes that are updated as incidents develop.

Historical wildfire perimeters are provided by CAL FIRE's Fire and Resource Assessment Program (FRAP). Once FRAP data become available for a wildfire, FEAST uses the FRAP records instead of the original incident data.

Depending on data availability and the time period, wildfires are represented by either an incident location point or a historical FRAP fire centroid point and perimeter boundary. Coverage: California statewide.

  • Wildfire Location: Approximate wildfire location from CAL FIRE incident data or the centroid of a historical FRAP fire perimeter. Incident locations do not necessarily represent the actual ignition point.
  • Wildfire Boundary (historical): Mapped perimeter of burned areas for documented wildfires, based on FRAP data.
Data sources:
  • Wildfire Location
  • Wildfire Boundary (historical)

Hazard Mapping System (HMS) provides near-real-time satellite detections of active fires and analyst-drawn smoke plume extents across North America. FEAST includes California-only subsets.

Data source: NOAA Office of Satellite and Product Operations (OSPO)
  • HMS Fire: Satellite fire detections (point)
  • HMS Smoke: Smoke plume boundary (gray outline)

  1. Use the checkboxes to show or hide layers (PM2.5, Ozone, Wildfires, HMS Fire/Smoke, etc.). Checked layers are visible; unchecked are hidden.
  2. Click icons/symbols (fire, smoke, monitor site, etc.) to open a popup with details (site ID, date, value, and more).
  3. Use the time slider or date controls to focus on a specific day or range.