This study was used oceanographic database in the Sea of Okhotsk between the period from 1929 to 2020 (131286 stations). The paper used gas hydrate dissociation parameters for the “pure methane-seawater” system obtained in the study by Dickens GR and Quinby-Hunt MS. The results have elucidated the spatiotemporal variability of distribution of such parameters at the upper boundary of the gas hydrate stability zone (GHSZ) as water temperature, salinity, and top depth of the stability zone. As the study has shown (based on average long-term spatial distributions), the minimum temperature and depth values of the GHSZ upper boundary in the Sea of Okhotsk occur off the western and southwestern parts of the water area. The maximum temperature and depth values of the GHSZ upper boundary are typical of the southeastern sea area and over the Kamchatka Peninsula slope. This study has also identified an area, where there are no thermobaric conditions for the emergence and stable existence of methane hydrates in the water column. The results presented agree well with the materials of observations conducted during expeditions and the previous data of predictive simulations for the Sea of Okhotsk.