A database of temperatures for large inland lakes across the coterminous U.S.

A standardized database of in situ water temperatures for large inland lakes across the coterminous United States compiles near-surface and subsurface measurements from 134 monitoring sites on 29 lakes, spanning 2000-2022 with emphasis on 2019 observations. The collection was assembled to provide validation data for NOAA’s Unified Forecast System (HRRR 1‑D lake models) and to support a Joint Technology Transfer Initiative testing alternative bathymetry (GLOBathy). Laurentian Great Lakes are excluded because they are represented with a separate 3‑D modeling framework. Eighty-four of the 134 sites include multi-depth profiles suitable for validating vertical temperature structure.

Temperature records were aggregated from federal repositories (NDBC, USGS NWIS, WQP) and local monitoring groups at the highest available temporal resolution, producing mixed-quality time series ranging from sub-hourly to monthly. The database includes metadata, mapped site locations aligned with 3‑km HRRR pixels, quality annotations, and plotting scripts to visualize sensor-specific characteristics. The resource enables rigorous evaluation of lake model performance, assessment of bathymetric-data impacts on simulated surface and depth temperatures, and empirical analyses to improve operational forecasts where large lakes influence regional weather and climate.