This dataset contains measurements collected for the study of the seasonal development of osmotic potential at full turgor in grapevine (Vitis vinifera cv. Pinot noir/SO4). Plants were grown under controlled greenhouse conditions at day temperatures of 20 °C, 25 °C, and 30 °C during 2022 and 2023, and under semi-controlled field conditions in 2023.These data support the manuscript “Leaf seasonal osmotic adjustment is not driven by temperature nor water deficit” (Farolfi et al., 2025), which is accepted for The Plant Journal (DOI https://doi.org/10.1111/tpj.70569). The article provides a detailed description of the material and methods. Data content:For each sampling date and treatment, osmotic potential at full turgor was measured, together with the molarity of major soluble sugars (glucose, fructose, sucrose, myo-inositol) and cations (calcium, potassium, magnesium). The dataset includes dates, treatment conditions, and measurement units. File format:All data are provided as .csv files. The README.txt reports the description of variables, units, and methods per each dataset. The following file and dataset are shared: Osmolytes.csv - Contains osmotic potential at full turgor, molarity of soluble sugars (glucose, fructose, sucrose, myo-inositol), and cations (Ca, K, Mg). Includes sheets Raw_Data and metadata. Temperature_greenhouse.csv - Records of experimental temperature conditions, relative humidity and vapour pressure deficit under greenhouse trials year 2022 and 2023. Temperature_semicontrolled_field_trial.csv - Records of experimental temperature conditions, relative humidity and vapour pressure deficit under field trial year 2023. Water_Potential.csv - Measurements of stem water potential taken between 12:00 and 14:00 through the Scholander chamber, including treatment conditions and units.