These data were compiled for the Altar Valley Conservation Alliance and the U. S. Fish and Wildlife Service to identify and quantify the spatial distribution of fine fuels in relation to wildfire management across jurisdictional boundaries. Objective(s) of our study were to map the 2021 annual distribution of the biomass (kg/ha) of fine fuels (grasses, shrubs, and forbs) for the whole of the Altar Valley, AZ, including the Buenos Aires National Wildlife Refuge. These data represent estimated biomass of fine fuels (kg/ha) at a 10-m resolution. These data were collected/created in September through October 2021 for the Altar Valley, located in Pima County, AZ, USA. These data were collected/created by the U.S. Geological Survey, Southwest Biological Science Center, based on destructive field sampling of vegetation biomass (clipped, dried, & weighed), modeling of non-destructively sampled vegetation biomass (height & cover) to destructively sampled vegetation, and linking estimates of biomass to remotely sensed data from the Sentinel-2 by application of machine learning techniques (random forest). These data can be used to understand the distribution and abundance of fine fuels in the Altar Valley for research and management.