<p>The continuous and significant rise of the sea surface temperature (SST) in the Eastern Mediterranean Sea over the past three decades is not uniform in temporal and spatial scales. This study investigated the temporal evolution of the SST in the Cilician Basin for the last forty years on monthly to decadal scales using three datasets obtained with different methodologies. “The High-Resolution Daily Optimum Interpolation SST” (OISST V2.1), the fifth-generation reanalysis (ERA5) “monthly averaged data on single-level”, and the in-situ observations were utilised to compare all datasets and analyse the temporal evolution of the SST in the region. The SST of the Cilician Basin has continuously increased at a rate of 0.037 to 0.051 ℃/yr between 1983-2023. Two opposite trends were observed during the studied period: a decreasing trend of –0.042 to –0.052 ℃/yr between 1983 and 1993 and an increasing trend since 1993. The OISST and In-Situ datasets were almost identical on the annual scale. In both datasets, about 0.042 ℃/yr of SST increases were recorded between 1995 and 2023. In both datasets, the highest warming is recorded in the Fall (September-December) (0.057 and 0.084 ℃/yr), and June is recorded with decreasing trends (–0.009 and –0.017 ℃/yr). In the ERA5 dataset, the SST is increased by 0.054 ℃/yr and the highest warming is recorded in Summer (0.070 ℃/yr). The highest three annual mean SST since 1983 were recorded in the last six years, and 2018 was the warmest year in the studied period. Significant SST warmings in November (0.097 ℃/yr) and December (0.084 ℃/yr) between 1995 and 2023, especially in 2017 and 2018, emerged from the In-Situ observations. This excessive warming (low-efficient cooling) in the Fall/early Winter is of particular concern as it may affect the physical/biochemical characteristics of the water column, hence the circulation and coastal ecosystem.</p>