Marine biofilms are the first stage of marine biofouling, however not much is known about their temporal succession. We used Illumina MiSeq-based pair-end 16S rRNA gene amplicon sequencing to characterize early marine biofilms growing on steel surfaces in a Northern Portugal port in two distinct seasons (Winter and Spring). Significant distinct temporal patterns were found, and we suggest that the reported temporal succession of early marine biofilm communities should be taken in consideration for future antifouling applications.