In Spain, mussels comprise around 90% of the total aquaculture production. Spanish mussel culture takes place almost exclusively in Galicia. The high productivity of the Galician coasts is a consequence of its western oceanic bound together with the seasonal northerly winds, generating strong upwelling of rich nutrient cold waters from May to September. When winds change to a southward direction, it results in a downwelling phenomenon which difficult the water renewal along the Galician Rias, contributing to the appearing of toxic blooms. The quantification on the degree of upwelling using the upwelling index serves as the basis for a predictive capability for harmful algal blooms (HABs). Where HABs occur at sufficient biomass, they may be detected by optical instruments, including ocean colour sensors on satellites together with sea surface temperature radiometers. Pairing of SST and pigment information allows the identification of key HAB processes and their relationship to physical dynamics. Results obtained in this study, indicate that there is a close relation between upwelling events, chlorophyll data, sea surface temperature and HABs. Therefore, all this parameters can be used to make a reliable prediction system of toxicity blooms in the Galician coast.