The evolution of the upper ocean in the strong seasonally forced Arabian Sea, as observed by a mooring deployed in 1994--1995, is investigated using the Naval Research Laboratory Layered Ocean Model (NLOM). Model simulations were sensitive to the choice of surface wind products used for forcing, and results are reported for simulations forced by monthly mean climatologies and 12 hourly 1994--1995 wind products from two operational atmospheric forecast models, the European Center for Medium-Range Weather Forecast model and the Navy Operational Global Atmospheric Prediction System model of Fleet Numerical Meteorology and Oceanography Center (FNMOC). The NLOM yields the best prediction of sea surface temperature (SST) and mixed layer depth when using FNMOC forcing. Surface cooling is found to be responsible for the seasonal SST minimum during the NE monsoon. Heat advection is found to be important for supporting the surface cooling during the second half of the NE monsoon. Strong entrainment and appreciable advective cooling are responsible for the SST minimum of the SW monsoon. The NLOM wind experiments strongly suggest that thermal convection may be important in the central Arabian Sea during the winter months. ¿ 2000 American Geophysical Union