The Configurable Scanning Submillimeter-wave Instrument/Radiometer (CoSSIR) IMPACTS dataset consists of data measured onboard the NASA ER-2 aircraft during the Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms (IMPACTS) field campaign. IMPACTS was a three-year sequence of winter season deployments conducted to study snowstorms over the U.S. Atlantic coast. IMPACTS aimed to (1) Provide observations critical to understanding the mechanisms of snowband formation, organization, and evolution; (2) Examine how the microphysical characteristics and likely growth mechanisms of snow particles vary across snowbands; and (3) Improve snowfall remote sensing interpretation and modeling to significantly advance prediction capabilities. The CoSSIR dataset consists of measured ice clouds and brightness temperatures, water vapor profiles, and snowfall rates. CoSSIR data are available from January 5, 2023, through March 2, 2023, in netCDF-4 format.