About the data

Current fires

Data for the map of current fires comes from a combination of data from the California Department of Forestry and Fire Protection, or CalFire, and the National Interagency Fire Center.

CalFire’s fire data only includes fires more than 10 acres within its jurisdiction. The information, according to CalFire, “comes from the firelines and must be approved by the Incident Commander in charge of managing the incident prior to release. As battling a fire, or handling any other disaster is the priority, updates to these sites cannot be guaranteed on a set time schedule.”

Fires outside of CalFire’s jurisdiction come from the NIRC’s WFIGS Current Interagency Fire Perimeters, which is gathered by firefighting and support teams on the ground.

The information from these two sources is combined and de-duplicated. Only fires 100 acres or greater with location information that have been updated in the last five days are displayed on the map.

Fire history

This data also comes from the National Interagency Fire Center, which in some cases has data up to 2023.

The graphs only go back to 1983, because prior to that, “the federal wildland fire agencies did not track official wildfire data using current reporting processes,” according to the NIRC.

The animated timeline map still shows fire data back through the 1950s for reference. The NIRC’s historical map data goes through 2021. This data is reported by local agencies and according to the NIRC, “fire perimeter data are often collected at the local level, and fire management agencies have differing guidelines for submitting fire perimeter data. Often data are collected by agencies only once annually.

Future fire risks

This information comes from climate non-profit, First Street Foundation. The data is based on First Street’s “Fire Factor” model, which is a “nationwide, fire-behavior-based wildfire model that forecasts a location’s probabilistic risk of wildfire based on vegetation, topography, and likely weather.”

The model takes information like fuel, drought and historical data and predicts future fire risk over the next 30 years as an index from 1 to 10 for properties in the U.S. Those indexes are then aggregated at the county and state level. The maps on this page represent “major” and “severe” fire risk. A property is at “major” risk if it has a fire factor of at least 5 is forecast to have at least a 6% to 14% percent chance of being directly damaged by wildfire at least once over 30 years. The model says “severe” risk means a property faces at least a 15% chance over that time.

Cost

Firefighting suppression costs come from the National Interagency Fire Center. The total number is made up of suppression costs from the Forest Service and U.S. Department of the Interior agencies.

The data goes through the most recent date available from the NIFC, which currently is 2023.

Air quality

AirNow.gov is managed by the EPA along with other federal and local state partners. Agencies across the country send their monitoring data to AirNow for display, updated every hour.

The data shows levels of fine particulate matter (PM2.5), which are particles 2.5 micrometers in diameter or smaller. These particles are so small they can be inhaled, causing serious health problems. The data also shows ozone levels, which can become harmful to health on hot, sunny days when ozone reaches unhealthy levels.

AirNow reports air quality using the Air Quality Index (AQI). The higher the AQI level, the greater the level of air pollution and the greater the health concern.

For example, an AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality.