US Forest Service Santa Ana Wildfire Threat Index (SAWTI) Forecast Guidance

The Santa Ana Wildfire Threat Index (SAWTI) categorizes Santa Ana winds based on anticipated fire potential. The index uses a comprehensive, state-of-the-art predictive model that includes dead fuel moisture, live fuel moisture, and the greenness of annual grasses to create a detailed daily assessment of the fuel conditions across Southern California. This information is coupled with calibrated weather model output (comprised of wind speed and atmospheric moisture), to generate a 6-day forecast of Large Fire Potential. The Large Fire Potential output is then compared to climatological data and historical fire occurrence to establish the index rating. The CSV data files are presented to the United States Forest Service (USFS) as the forecast guidance. The official SAWTI rating may differ from that calculated directly from the guidance as adjustments may be made by the on-duty forecaster.

Data and Resources

Additional Info

Field Value
Last Updated September 1, 2025, 05:25 (UTC)
Created February 28, 2024, 17:06 (UTC)
accessRights For access rights, refer to the license: https://sdge.sdsc.edu/data/sdge/sawti/LICENSE
creationMethod Learn more about dataset's creation method at the "About" page of the "Santa Ana Wildfire Threat Index" page (https://fsapps.nwcg.gov/psp/sawti/about) and at the paper detailing the purpose of the SAWTI dataset (https://journals.ametsoc.org/view/journals/wefo/31/6/waf-d-15-0141_1.xml).
creatorEmail meteorology@semprautilities.com
creatorName San Diego Gas & Electric (SDG&E) Meteorology Team
creatorWebsite https://sdgeweather.com/
dataAuthType public
dataType CSV
datasetPageUrl https://journals.ametsoc.org/view/journals/wefo/31/6/waf-d-15-0141_1.xml
docsURL https://journals.ametsoc.org/view/journals/wefo/31/6/waf-d-15-0141_1.xml
doi https://doi.org/10.1175/WAF-D-15-0141.1
harvest_object_id 06d6a05e-ffed-417b-a648-41e9cd0bbb70
harvest_source_id a2637971-af12-457f-ae4a-831d2202a539
harvest_source_title WIFIRE Commons
issueDate 2014-04-07
lang en
lastUpdateDate 2025-08-27
license other
pocEmail meteorology@semprautilities.com
pocName San Diego Gas & Electric (SDG&E) Meteorology Team
pocWebsite https://sdgeweather.com/
publisherEmail meteorology@semprautilities.com
publisherName San Diego Gas & Electric (SDG&E) Meteorology Team
publisherWebsite https://sdgeweather.com/
purpose Santa Ana winds, common to Southern California from the fall through early spring, are a type of downslope windstorm originating from a direction generally ranging from 360°/0° to 100° and are usually accompanied by very low humidity. Since fuel conditions tend to be driest from late September through the middle of November, Santa Ana winds occurring during this time have the greatest potential to produce large, devastating fires upon ignition. Such catastrophic fires occurred in 1993, 2003, 2007, and 2008. Because of the destructive nature of such fires, there has been a growing desire to categorize Santa Ana wind events in much the same way that tropical cyclones have been categorized. The Santa Ana wildfire threat index (SAWTI) is a tool for categorizing Santa Ana wind events with respect to anticipated fire potential. The latest version of the index has been a result of a three-and-a-half-year collaboration effort between the USDA Forest Service, the San Diego Gas and Electric utility (SDG&E), and the University of California, Los Angeles (UCLA). The SAWTI uses several meteorological and fuel moisture variables at 3-km resolution as input to the Weather Research and Forecasting (WRF) Model to generate the index out to 6 days. In addition to the index, a 30-yr climatology of weather, fuels, and the SAWTI has been developed to help put current and future events into perspective.
status submitted
theme ["santa-ana-winds"]
timezone PST
updateFreq Every 12 hours
uploadType dataset
usageInfo To access the data, navigate to the main data repository at https://sdge.sdsc.edu/data/sdge/sawti/. The data are organized into sub-folders titled using the format "Zone#-Region" (e.g., Zone1-LA-Ventura). Click on the desired sub-folder to access the corresponding data files, i.e., CSV files. Within each CSV file, the data are structured with variables listed in the first column and corresponding values organized by date in the subsequent columns. The dates are included in the "name" row. NOTE: CSVs can ONLY be downloaded INDIVIDUALLY. At the moment, you cannot download the CSVs for a given Zone as a .zip file. The variables listed in the CSV files are defined as follows: (1) NAME: Date of Observation, (2) NDVI: Normalized Difference Vegetation Index (remote sensing index to quantify greenness by subtracting red light reflectance from near-infrared light reflectance, and dividing the difference by the sum of the two; NDVI values for Southern California grasslands generally range from about 0.25 (±0.05) to 0.75 (±0.05) for an average rainfall year), (3) G: Greenness (degree of green-up of annual grasses, ranges between 0-5), (4) LFM_C/V/F/M: Live Fuel Moisture (LFM) values, (5) ERC: Energy Release Component (relative index of the amount of heat released per unit area in the flaming zone of an initiating fire; composed of live and dead fuel moisture as well as temperature, humidity, and precipitation), (6) F10: 10-hour dead fuel moisture [time required for dead fuels (0.64–2.54 cm in diameter) to lose approximately two-thirds of their initial moisture content; values are grams per gram expressed as a percentage ranging from 0 to 60], (7) F100: 100-hour dead fuel moisture [time required for dead fuels (~2.00 cm in diameter) to lose approximately two-thirds of their initial moisture content; values are grams per gram expressed as a percentage ranging from 0 to 60], (8) DL: Dryness Level (function of Energy Release Component, i.e., ERC, and 10-hour Dead Fuel Moisture, i.e., DFM, calibrated to historical fire occurrence across Southern California with unitless values ranging from 1 to 3), (9) DL/LFM: Dryness Level to Live Fuel Moisture ratio, (10) FMC: Fuel Moisture Content, (11) LFP_W: Large Fire Potential - Weather Component (the potential for a new ignition to reach or exceed 100 ha based solely on weather conditions during a Santa Ana wind event), (12) LFP: Large Fire Potential (the potential for a new ignition to reach or exceed 100 ha based on fuels and weather conditions during a Santa Ana wind event), (13) DD: 2-meter dew point depression in degree F, and (14) W^2: Squared 10-meter wind speed in mph. A more detailed description of the aforementioned variables and their role in the SAWTI can be found at this paper link (also included in the "Documentation" section of metadata): https://journals.ametsoc.org/view/journals/wefo/31/6/waf-d-15-0141_1.xml.