The High Altitude LIDAR Observatory (HALO) WHyMSIE dataset provides observations on aerosols and water vapor. The HALO instrument was carried aboard NASA’s Gulfstream III (G-III) research aircraft. HALO is used to characterize distributions of atmospheric composition. From an airborne platform, the HALO instrument provides nadir-viewing profiles of water vapor and profiles of aerosol and cloud optical properties. These data were collected during the Westcoast and Heartland Hyperspectral Microwave Sensor Intensive Experiment (WHyMSIE) field campaign. WHyMSIE aimed to capture a wide variety of thermodynamic, moisture, and planetary boundary layer regimes across a variety of surface types. The campaign flew over a variety of land and ocean environments. Comparing HALO and other datasets with hyperspectral microwave retrievals from CoSMIR-H and in situ temperature and humidity information will allow for scientific advancement of remote-sensing techniques into the hyperspectral microwave era and improved understanding of the planetary boundary layer at different measurement scales. The WHyMSIE G-III HALO dataset files are available from October 27, 2024 through November 15, 2024, in HDF5 format. Browse images in PNG format are also available.