The Hot-Dry-Windy Index (HDW) is a new index produced by USDA that is now available online at https://hdwindex.fs2c.usda.gov/index.html. It was designed to help users determine which days are more likely to have adverse atmospheric conditions that make it more difficult to manage a wildland fire. It combines weather data from the surface and low levels of the atmosphere into a first-look product.
HDW was designed to be very simple – a multiplication of the maximum wind speed and maximum vapor pressure deficit (VPD) in the lowest 50 or so millibars in the atmosphere. Because HDW is affected by heat, moisture, and wind, seasonal and regional variability can be found when comparing HDW values from different locations and times.
You can get the forecast for your location up to 6 days ahead by clicking on the map on the website above. This might be helpful in planning for controlled burns with changing weather conditions, since you would not want to burn on a day when the weather might cause a fire to spread out of control.
