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The Sea Surface Temperature (SST) of the western Indian Ocean shows a bimodal distribution caused by insolation changes and the migration of the Inter-Tropical Convergence Zone. Moreover, on inter-annual timescales, the western Indian Ocean is influenced by two monsoon periods and two seasonally-occurring events, the Indian Ocean Dipole (IOD) and the El Niño Southern Oscillation (ENSO). An understanding of paleoclimate is essential to better understand these ocean-atmosphere interactions and be able to predict future climate variability. Chemical analyses of corals allow us to reconstruct SST changes in high resolution (monthly-seasonal) and therefore help us to link them to seasonal insolation pattern variations caused by orbital forcing. Here, we use a Sr/Ca record of a fossil Porites coral, which is dated to the mid-Holocene (6k) and covers 16 years. Sr/Ca-ratios were measured using ICP-OES with simultaneous data acquisition. The results show variations in the bimodality and average maximum temperatures of each year. A sudden increase in SST by 1.66° C lasted for about 5 years and suggests a possible positive IOD/ENSO-event.