PRISM Weather Data

All data and models were processed on Beocat, the high-performance computing cluster at Kansas State University (https://beocat.ksu.edu/).

Weather variables are derived from the Parameter-elevation Regressions on Independent Slopes Model (PRISM) dataset, which provides daily gridded weather data at approximately 2.5 × 2.5 mile resolution. Degree-day measures follow the interpolation procedures described in Schlenker and Roberts (2009) and Tack et al. (2015).

Daily PRISM variables were aggregated to the county level as weighted means of all PRISM grid cells intersecting each county. Weights were based on the proportion of each grid cell associated with the relevant crop’s planted area, as derived from NASS Cropland Data Layers (CropScape), 2008–2024 (USDA NASS, 2019). County-level daily degree days and precipitation were then summed or averaged over each year’s growing season.

The growing season was defined using USDA crop progress reports. For each crop and state, the season begins when at least 10 percent of acreage has been planted and ends when at least 90 percent has been harvested. Weekly progress reports were converted to calendar dates to determine season length. Crops planted in one year and harvested in the next (e.g., winter wheat) were handled accordingly. When crop-state-year observations were missing, long-run average planting and harvest dates were used for imputation.

References

Schlenker, Wolfram, and Michael J. Roberts. 2009. “Nonlinear Temperature Effects Indicate Severe Damages to U.S. Crop Yields under Climate Change.” Proceedings of the National Academy of Sciences of the United States of America 106 (37): 15594–15598. https://doi.org/10.1073/pnas.0906865106.

Tack, Jesse, Andrew Barkley, and Lawton Lanier Nalley. 2015. “Effect of Warming Temperatures on US Wheat Yields.” Proceedings of the National Academy of Sciences 112 (22): 6931–6936. https://doi.org/10.1073/pnas.1415181112.

USDA National Agricultural Statistics Service. 2019. “CropScape – Cropland Data Layer (2019 Release).” https://nassgeodata.gmu.edu/CropScape/.