We provide experimental data from a mesocosm study in a seawater basin (L: 8.5 m x W: 2.0 m x H: 0.8 m). Changes in sea surface temperature and salinity were investigated under different wind speeds, solar radiation levels, and turbulence conditions. Seven experiments were performed at the Sea sURface Facility (SURF; Institute of Chemistry and Biology of the Marine Environment; 53.5148 °N, 8.1463 °E) in late summer 2024. Each experiment generally lasted for 22h, running from 22:00 UTC to 20:00 UTC the following day. Four different wind conditions were applied: no wind (level 0), low wind (level 1), medium wind (level 2), and strong wind (level 3). The basin was equipped with a cooling unit, which was used to differentiate between two levels of turbulence: on (flow generated by pumps) and off (no flow). Water temperature control with a hysteresis of 1 °C was applied in some of the experiments. Various parameters were measured during the experiments. High-resolution temperature sensors captured temperatures at multiple depths at a specific location and distributed measurements across the basin. Conductivity, temperature, and depth (CTD) sensors recorded the temperature and conductivity at various depths, enabling the calculation of absolute salinity using the thermodynamic equation of seawater 2010 (TEOS-10). Further measurements included air temperature and humidity at multiple positions over the basin, wind speed, wave height, incoming and reflected shortwave radiation, downward and upward longwave irradiance, and evaporation. To quantify turbulence, acoustic doppler velocimeters (ADV) were positioned at two depths (13 cm and 37 cm) to measure the three-dimensional velocity components. These data were used to calculate turbulent kinetic energy (TKE) in 15-minute intervals. The dataset offers valuable insights into small-scale variations in sea surface temperature and salinity under changing heat flux conditions, focusing on latent and shortwave heat fluxes to enhance our understanding of their counteracting effects.