Wildfire
Data Limitations
A systematic, national collection of wildfire reports did not begin until the early 1990s. Many analyses are based on only a few years of data, which may not capture multi-year variability or trends. Further, fires accounted for by local jurisdictions may not always translate into national databases.
Definition and Description
Any free burning uncontainable wildland fire not prescribed for the area which consumes the natural fuels and spreads in response to its environment (NWS 2009).
Wildfires occur when weather conditions meet with sufficient fuel and an ignition source. Weather conditions include warm temperatures, low humidity, strong winds, and a period without precipitation allowing fuels to dry. Fuels are vegetation ranging from fine fuels such as grass and pine needles to large woody materials such as trees, dead and decaying logs, and organic material in the soil. Large woody materials are difficult to ignite; the presence of fine fuels allows fire to get started and become intense enough to ignite larger materials. Ignition sources may be natural, such as lightning, or human-caused, such as sparks from equipment, power transformers, a chain dragging behind a vehicle, or heat sources, such as discarded cigarettes.
There are two wildfire “seasons” in Oklahoma, although they can happen in any month. Fires are a common occurrence in late winter when dormant vegetation provides fine fuels and warm, windy, dry days provide weather conditions that allow ignition and spread. Summer has higher temperatures that can allow fires to become very intense, but there is typically less wind and consequently less spread. Fire spread may be increased on south-facing slopes, which are usually drier and warmer because of exposure to the sun, windy locations such as canyons, and along steep slopes. Very intense fires may become “crown fires” if they burn to the tops of trees, allowing embers to spread farther and create spot fires. Crown fires are almost impossible to extinguish without cooler, wetter weather conditions.
Fire danger is measured on a Burning Index scale, ranging from 0 to 110+. Values below 20 are considered low fire potential, 40-80 is high, and 110 or higher is extreme. The burning index combines potential energy release (fire intensity), flame length, and rate of spread. The National Weather Service issues Red Flag Warnings when weather conditions are favorable for ignition and spread of wildfires. Another popular index is the Keetch-Byrum Drought Index (KBDI) that considers weather and vegetation conditions. The scale ranges from 0 to 800; values below 200 indicate high fuel moisture making ignition unlikely; values above 600 are indicative of intense wildfire conditions with any that develop capable of downwind spotting (starting new fires).
Historical Data
SPC Data Viewer - Wildfire Climatology
(1992-2020)NOAA/NWS Storm Prediction CenterThis tool provides a wildfire climatology for daily, monthly, yearly, and seasonal time scales. It can be used to assess the time of year with the highest probability of wildfires. The tool also provides a climatology for other hazards (e.g., any severe storm, lightning, wind, hail, tornado).
1. Within the Hazard drop-down menu, select Fire. 2. Within the Climatology Interval menu, select the option you are interested in. For all options other than Yearly, there is a horizontal scroll bar under the map to change the map view to each day, month, or season of the year. Note: Read the title and colorbar for each selection, as there are differences in what is shown. 3. Within the Threshold menu, select the number of acres. 4. Under Map Overlays, check any layers of interest. 5. Click your area of interest on the map to view the probability of wildfire for your selection. 6. Use the download feature to receive a clean output map for the full U.S. with a legend. 7. Read more about the probability calculations and map information in the About section.
Wildfire Risk to Communities
(Varies by data layer; fire occurrence: 1992-2020, fuelscape: 2020)USDA Forest ServiceThis tool provides information and resources for communities to understand, explore, and reduce wildfire risk. Mitigation resources and programs for action are provided in the Incentive and Action Programs for Hazard Risk Reduction menu item, but this segment of the tool allows users to explore risk for a community, tribal area, county, or state. This tool provides several charts and maps about wildfire risk and compares the risk of your selected area to other jurisdictional levels.
1. In the search bar, enter your desired community, tribal area, county, or state. 2. On the results page, you’ll see a summary statement comparing your selected area’s wildfire risk to the rest of the nation. Below this is a summary of the risk to homes, wildfire likelihood, risk reduction zone, and vulnerable populations, with a risk of low to high. 3. Select one of these risk categories to view more information and access an interactive map. 4. The resulting page includes a summary statement, interactive map, descriptive information about that risk, and action information. 5. The Risk to Homes and Wildfire Likelihood options include an interactive graph of percentiles that compares your selected area to others. The default geographic comparison is Nation but you can select a different option (e.g., county or state) from the Compare to drop-down menu at the top of the page. Hover over the points on the graph to explore the information (red points represent higher risk or likelihood). Switch to other risk pages by using the tabs on the top of the page.
Southern Wildfire Risk Explorer
(data derived from risk assessments updated in 2024)Southern Group of State ForestersThis interactive tool can be used to identify areas within and/or near a city that are at greatest risk of wildfire. It is especially useful for identifying risk areas in the wildland-urban interface and to help prioritize areas where tactical analyses, community interaction, or mitigation treatments might be necessary to reduce risk. The Advanced Viewer option allows users to generate reports and download data for their project area. Note: There is a learning curve associated with this tool. Basic Viewer is accessible to anyone but is limited. Advanced Viewer is also free but requires account request.
1. Scroll down to the Tools section and click Southern Wildfire Risk Explorer. 2. On the next page, select Basic or Advanced Viewer. The following instructions are for the Advanced option, as map layers a very limited for the Basic option. 3. Click Assess Your Location on the top of the page. Pan and zoom in on the map to center the black dot on your area of interest. The left panel displays the overall Wildfire Exposure Score and a short description about the need to implement mitigation actions. 4. Click on Map Themes on the top of the page. There are several map layer options on the left-hand menu. Select the layer you want to view and see details about each layer by hovering over the circular “i” icon. 5. To compare two layers, click on the second icon (divider) under the search bar at the top right of the page. 6. Click Project Areas at the top of the page to ultimately generate a comprehensive risk summary report for your area and export data. 7. Create your own project boundary using a custom shape that you draw on the map, select from a reference layer, or upload a shapefile. 8. After creating a project boundary, click Create at the bottom of the left panel. You can then enter your email address, click the button to generate a summary report or export data, and click the send button next to your email. Note: Data are displayed at a very fine (25-meter) resolution, so you may need to greatly zoom in to view more details on the map. To read more details about each map layer and the project areas feature in the user manual or download state-specific data packages, please visit https://southernwildfirerisk.com/riskexplorerresources/.
Prescribed Fire Climatology
(1996-2015) Southern Climate Impacts Planning ProgramThis scientific report includes a series of static graphics and tables. It can be used to identify the best months to conduct prescribed burns as a wildfire management strategy. Coupled with tools such as SouthWRAP, one can target locations and timing for safe burning along the wildland-urban interface. The report describes the average, minimum, and maximum number of days with a consecutive 4-hour period suitable for prescribed fire as a management tool to reduce vegetation fuel load and improve vegetation health.
1. Click on the report link. 2. Tables and Figures relevant to Oklahoma: Tables 2 and 7, Figures, 7, 8, 13- 17, 25.
Wildland-Urban Interface
(1990, 2000, 2010, 2020) University of Wisconsin-Madison SILVIS LabThis interactive tool shows WUI (Wildland-Urban Interface) in 1990, 2000, 2010, and 2020 for locations of interest.
1. Zoom into desired location(s) on map. 2. On left side of screen, select year → base map → and layer opacity of interest. Note: Oklahoma-specific data and map files (down to the county level) are available by scrolling down the page
Wind Rose Plots
(Period of record varies by station; up to ~85 years) Iowa Environmental Mesonet, Iowa State UniversityView common and prominent wind speeds and directions for your area. Plots can be viewed either by month or by the full years on record. This tool can be used to describe general climate and the predominant direction in which air pollutants flow. It may also be useful for understanding how wildfire events may evolve or play out in a community.
1. In the Select By Network section, choose Oklahoma ASOS then click Switch Network. 2. Select station of interest, either from list or map, then click Select Station. 3. You will be brought to a new page. Near the top of the page, click on the Wind Roses tab. 4. Yearly climatology is displayed at the top of the page and monthly climatologies are displayed below that. Click View Raw Data on any plot to view more details.
Climate Change Trends
Between 1984 and 2011, the number of large wildfires increased in the Southern Plains, which includes Oklahoma (Wehner et al. 2017). Wildfires in Oklahoma are dependent upon current weather conditions, seasonal climate patterns, vegetation conditions, and an available source for ignition (such as a spark, flame, or intentional). Given this complex relationship, the future trend for wildfire is also complex. However, projected increases in temperatures that can dry fine fuels such as grasses and enhanced wet/dry cycles that promote vegetation growth and drying or dormancy, coupled with population growth along the wildland-urban interface, suggests the risks of wildfires is likely to continue to increase. Read more about future wildfire risk in Climate Change Science and Projection Resources.