The Indian summer monsoon (ISM) brings most of the annual precipitation to the densely populated region in southern Asia. For the agricultural development and economic prosperity of the region, it is therefore vital to assess the variability of the monsoon system on societal relevant decadal- to centennial time scales. This might help to better understand how potential driving forces might be controlling ISM variability and how it might develop under future climate scenarios. Here we present a study of a sediment core from the northern Oman margin, revealing early- to mid Holocene ISM conditions on a near 20-year resolution. We assess multiple independent proxies indicative of sea surface temperatures (SST) during the upwelling season together with bottom water conditions. We use geochemical parameters, transfer functions of planktic foraminiferal assemblages and Mg/Ca paleothermometry and find evidence corroborating previous studies that upwelling intensity varies significantly in coherence to solar sunspot cycles. The dominant ~80–90-year Gleissberg cycle was apparently also affecting bottom water oxygen conditions. Although the interval from 8.4 to 5.8 ka B.P. is relatively short, the gradually decreasing trend of summer monsoon conditions was interrupted by short events of intensified ISM conditions. Results from both independent SST proxies are linked to phases of weaker OMZ conditions and enhanced carbonate preservation. This indicates that atmospheric forcing was intimately linked to bottom water properties and state of the OMZ on decadal time scales.