The text file "Wind speed.txt" contains hourly wind speed data in miles per hour and associated data source flags from January 1, 1948, to September 30, 2020. The primary data for water year 2020 (a water year is the 12-month period, October 1 through September 30, designated by the calendar year in which it ends) were downloaded from the Argonne National Laboratory (ANL) (Argonne National Laboratory, 2020) and processed following the guidelines documented in Over and others (2010). The processed data were appended to ARGN19.WDM (Bera, 2020) and renamed as ARGN20.WDM. Missing and apparently erroneous data values were replaced with adjusted values from nearby weather stations used as “backup”. The hourly wind speed data from the Illinois Climate Network (Water and Atmospheric Resources Monitoring Program, 2020) station at St. Charles, Illinois, and the National Weather Service station at O'Hare International Airport were used as "backup". Midwestern Regional Climate Center (Midwestern Regional Climate Center, 2020) provided the data collected by National Weather Service from the station at O'Hare International Airport. Each data source flag is of the form "xyz", which allows the user to determine its source and the methods used to process the data (Over and others, 2010). References Cited: Argonne National Laboratory, 2020, Meteorological data, accessed on November 17, 2020, at http://gonzalo.er.anl.gov/ANLMET/. Bera, M., 2020, Meteorological Database, Argonne National Laboratory, Illinois, January 1, 1948 - September 30, 2019: U.S. Geological Survey data release, ​https://doi.org/10.5066/P9X0P4HZ. Midwestern Regional Climate Center, 2019, Meteorological data, accessed on November 3, 2020, at https://mrcc.illinois.edu/CLIMATE/. Over, T.M., Price, T.H., and Ishii, A.L., 2010, Development and analysis of a meteorological database, Argonne National Laboratory, Illinois: U.S. Geological Survey Open-File Report 2010-1220, 67 p., http://pubs.usgs.gov/of/2010/1220/. Water and Atmospheric Resources Monitoring Program. Illinois Climate Network, 2019. Illinois State Water Survey, 2204 Griffith Drive, Champaign, IL 61820-7495. Data accessed on November 9, 2020, at http://dx.doi.org/10.13012/J8MW2F2Q.