Over the years, a remarkable growth in the installation of offshore wind turbines (OWTs) has been noticed since OWTs are great clean and green energy sources. Moreover, floating offshore wind turbines (FOWTs) have been deployed in deep ocean beds to exploit large ocean areas to extract vast, steady wind resources. Spar type FOWTs are highly complex structures consisting of different mechanical, electrical components which affects their overall dynamics under different environmental and operational conditions. But these slender, taller structures when installed in deep ocean beds are subjected to constant wind-wave-current loading, which poses fatigue and can cause unexpected failure of FOWTs in extreme ocean environments. Hence, structural health monitoring (SHM) of FOWTs can significantly contribute to maintaining their structural integrity. SHM of FOWTs has been an active research area among the scholars to identify the highly challenging damages. It is also crucial as damage in mooring cables significantly alters the dynamics of FOWTs. Therefore, this study investigates the effects of environmental and operational conditions on SHM of a spar type FOWT. The damage scenarios corresponding to marine growth and corrosion on mooring of a 5MW NREL OC3-hywind spar FOWT, are considered. Numerical simulations are carried out in OpenFAST, considering the severe environmental and operational conditions (EOC) from a site located in the northern coast of Scotland. The acceleration responses at several points along the tower of the healthy and damaged turbines are accumulated and a data driven technique is adopted for damage identification.