We describe atmospheric temperature inversions and height-resolved water vapor fields over the wintertime subtropical northeastern Pacific Ocean in observations by the satellite-borne Atmospheric Infrared Sounder (AIRS) experiment. A comparison with model analyses shows good agreement in temperature. Water vapor comparisons with operational radiosondes at four sites in California and Hawaii during December 2002–January 2003 have low biases in the 1000–700 and 700–500 hPa layers. Maps of inversion frequency, and, water vapor at 1000–700 and 700–500 hPa over the subtropical northeast Pacific during 1–16 January 2003–when high pressure and clear conditions prevail–show inversions occurring at a local minimum in water vapor at 1000–700 hPa. Water vapor at 700–500 hPa has a broad minimum extending from Baja California to Hawaii, with inversions found on its eastern half. These observations illustrate the potential of the AIRS data for describing a climatology of temperature and water vapor in subtropical oceanic regions.