WhenToApplyPreEmergent ZIP/ZCTA Growing Degree Days (base 50°F)

Derived daily cumulative growing degree day dataset (base 50°F) for 33,642 U.S. Census ZIP Code Tabulation Areas (ZCTAs) across the 50 states and District of Columbia. Values accumulate from 2026-01-01 using NOAA GHCN-Daily TMAX and TMIN observations from the nearest sufficiently fresh station among eight candidates; geography and representative points come from U.S. Census ZCTA sources. This immutable 2026-07-16 snapshot contains 33,622 available rows and 20 unavailable rows. Selected-station observation end dates range from 2026-07-09 through 2026-07-13. Files include the national dataset in CSV and Parquet, state summaries, schemas, a sample, metadata, machine-readable citation, licensing terms, and SHA-256 checksums. Canonical dataset: https://whentoapplypreemergent.com/datasets/gdd/Immutable release: https://whentoapplypreemergent.com/datasets/gdd/2026-07-16/Reproducibility documentation and code: https://github.com/ke-pan/us-zip-gdd-dataset Limitations: ZCTAs are Census statistical areas, not USPS delivery-area boundaries. Nearest-station assignment by representative point may not capture local microclimates. Unavailable rows are retained explicitly. The project derives this compilation from NOAA and U.S. Census source materials and does not claim to have collected the underlying thermometer observations.