Benjamin-Feir Index (BFI) and directional spread are measures of nonlinear four-wave interactions and resultant indices of possible potential conditions for freak waves. Temporal-spatial distributions of BFI and directional spread are examined by numerical simulations using a spectral wave model with analysis data of ERA-40. The spatial distributions of wave characteristics such as significant wave height, wave period, BFI and directional spread are simulated in a global scale. Freak waves resulting from nonlinear four-wave-wave interactions have a greater potential of occurring in the western edge of ocean basin. Furthermore, dependence of BFI on wave age in short fetch can be observed.