Abstract: The possible relation of the Arabian Sea Warm Pool (ASWP) with monsoon onset over Kerala is studied by utilizing the TRMM Microwave Imager data during the period 2007 - 2011 (5 years). The ASWP is a part of the Indian Ocean warm pool and forms in the Arabian Sea prior to the monsoon onset over Kerala (MOK) during the pre-monsoon months (April and May). The main focus of the present work is to look into the evolution of ASWP and its association, if any, with different types of MOK. The analysis revealed that there exist a lag of 16 days between the date of maximum intensity of ASWP and MOK. The ASWP started its dissipation immediately after attaining its peak intensity. It was also found that the extent and intensity of the ASWP showed large inter-annual variability. The number of warming events also showed large variability during these periods