Wildfires can potentially spread fastest when they tear through areas of dry vegetation. In contrast, vegetation that contains a lot of moisture can slow a wildfire’s advance and give firefighting crews precious time to contain the blaze.

Because dryness is such a critical driver of wildfires, a team of scientists at the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR) is producing maps in real time of the moisture content of vegetation across the United States, as well as adjacent areas of Canada and Mexico. The maps, which include both living and dead vegetation (or fuel, as the wildfire community calls it), are updated hourly to daily, depending on the location. They are available to view on a dedicated NSF NCAR webpage.

The map above, for example, shows the moisture content of small dead fuels, such as twigs, on September 20, 2026. It highlights the especially high wildfire risk across much of the West, especially in areas of southern California, Nevada, and Arizona, as well as more moderate risk in the Southeast and upper Midwest.

To create the maps, a team of NSF NCAR fire experts, meteorologists, and machine learning specialists drew on advanced weather models as well as observations of land cover and atmosphere, including data from two NASA and NOAA satellite instruments: the polar-orbiting Visible Infrared Imaging Radiometer Suites, or VIIRS; and the geostationary Advanced Baseline Imager, or ABI. 
This information was fed into a machine learning model, which estimates the moisture of vegetation at a resolution as fine as 375 meters across the contiguous United States and Alaska, and 750 meters in Hawaii.

The work is funded by NOAA with the goal of helping to highlight regions of higher and lower risk year round.

The team began producing the maps in 2023 and continually improves them. This year, they added an important new feature: the ability to view the moisture content of trees, shrubs, and grasses separately. This is vital because different types of plants can store moisture or dry out on widely varying time scales, so a fire that rapidly consumes dry grass might behave much differently if it enters a grove of trees that are somewhat moist.

“Understanding specifically the moisture levels in these different fuels is very important,” said NSF NCAR scientist Pedro Jimenez Munoz, who is leading this research. “Getting the fuel moisture content right is necessary for modeling the fires accurately and being able to identify which regions are at risk and how quickly a wildfire will spread.”

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