U.S. County-Level Compound Drought–Heatwave (CDHW) Occurrence Dataset, 2000–2021

This dataset provides county-level estimates of compound drought–heatwave (CDHW) occurrence across the contiguous United States from 2000 to 2021. CDHWs were identified by combining weekly U.S. Drought Monitor (USDM) drought classifications with daily maximum temperature data from the Climate Prediction Center (CPC). A county was considered drought affected when at least 75% of its grid cells were classified as D0 (abnormally dry) or higher. Extreme-heat days were identified when county-level daily maximum temperature was equal to or greater than the county-specific 90th percentile of May–October temperatures during 2000–2021. CDHW days represent the daily co-occurrence of drought and extreme-heat conditions, and CDHW events were defined as at least three consecutive CDHW days. The dataset includes county-level CDHW event frequency across four severity classes corresponding to D0, D1, D2, and combined D3/D4 drought conditions coinciding with extreme heat.