The Neversink River watershed (above the Neversink Reservoir) has been a focus of U.S. Geological Survey research for decades regarding stream geochemistry, acidification, and ecology dynamics. In 2019, the Water Mission Area Next Generation Water Observing Systems Program (NGWOS) augmented the existing stream gage network to include multiscale instrumentation aimed at characterizing various aspects of groundwater discharge to streams. Groundwater discharge from hillslopes and underlying aquifers acts as an important component of stream baseflow, and influences stream thermal regimes. This data release contains three data types that could potentially be used to infer spatiotemporal variability in groundwater discharge processes, along with other research and monitoring purposes: 1) Stream channel water and adjacent streambank air temperature time series data (generally starting November 2020); 2) Discrete stream stable water isotope data (May 2021 and October/November 2021); and 3)Discrete samples of dissolved radon gas from stream water (collected May 2021). Data were collected at 51 temporary stations installed along the east branch, west branch, and mainstem of the Neversink River, along with several perennial tributaries to the primary river branches. Air and stream temperature time-series data vary in spatial and temporal coverage as detailed in the ?Processed_data? directory output temperature matrices resampled at a daily timestep. In contrast, stable water isotope and radon data were collected at most but not all stream temperature sites, and a few hillslope groundwater discharge locations, as detailed in the ?Raw_data? directory. Details regarding the specific instrumentation and lab analysis used are listed in the ?README_raw? text file located in the ?Raw_data? directory. Additionally, the locations of paired stream and air temperature data can be accessed as a shapefile ?XYTidbits_deployed_final.shp?. Stable water isotope data were also collected along the mainstem of the upper Delaware River (starting at Handcock New York) from June 27 to July 1, 2021 for a related project, and those data are also included here in the ?Raw_data? directory.