The U.S. Geological Survey (USGS), in cooperation with the State of Hawaiʻi Department of Transportation, estimated flood magnitudes for the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (AEP) for unregulated streamgages in Kauaʻi, Oʻahu, Molokaʻi, Maui, and Hawaiʻi, State of Hawaiʻi, using data through water year 2020. Regression equations which can be used to estimate flood magnitude and associated frequency at ungaged streams were developed. The methods and results of the study are published in a separate report (https://doi.org/10.3133/sir20235014). This data release contains (1) a folder with the PeakFQ output files for each streamgage, ".PRT" and ".EXP" files, for use in the USGS weighted-multiple-linear regression (WREG) program; (2) a tab-delimited text file that contains the basin characteristics for use in the USGS WREG program; and (3) a folder with the output from the USGS WREG program, with results separated into folders for each regression region and selected AEP. These data can be used to reproduce the regression results in the larger work: Magnitude and Frequency of Floods on Kauaʻi, Oʻahu, Molokaʻi, Maui, and Hawaiʻi, State of Hawaiʻi, Based on Data through Water Year 2020.