A cyclogenesis index (CSGP) is introduced and its variations have been evaluated for the period 1979 to 2008. It is found that CSGP is able to distinguish different categories of storms over North Indian Ocean. The relative roles of contributing parameters are analyzed to study the influence of CGSP with respect different background states. It is found that vorticity, convergence, relative humidity and convective instability should be high enough to offset the negative impact of shear parameter.