This archive includes two .nc files (NetCDF format) containing observational data (discrete and mooring) from marine surface waters of the Pacific Northwest that have not yet been submitted to a long-term data repository. These data contributed to the development of seasonal cycle data products described in the manuscript by Fassbender et al. A metadata file is provided for the discrete data subset (upper 10 m of discrete observational data); however, the complete cruise datasets and metadata will be submitted for archival in the National Centers for Environmental Information’s (NCEI) Ocean Carbon and Acidification Data repository (https://www.nodc.noaa.gov/oceanacidification/). Data subsets are provided here for accelerated public access. Data users are encouraged to download the complete datasets from NCEI once they are available (https://www.nodc.noaa.gov/oceanacidification/stewardship/data_portal.html). Metadata for the University of Washington Oceanic Remote Chemical/Optical Analyzer (ORCA) mooring observations used by Fassbender et al., including the temperature and salinity data from the Dabob Bay and Twanoh moorings, are not provided here. Quality control protocols applied to the ORCA mooring data are outlined in the Quality Assurance Project Plan (http://nwem.ocean.washington.edu/ORCA_QAPP.pdf; Newton and Devol, 2012).