Increased rainfall over this weekend could lead to more bacteria in the water at Ballyloughane and Grattan Road beaches.
Galway City Council issued a warning to bathers today to avoid swallowing or splashing water at the two Galway beaches.
People are also advised to wash their hands before eating, avoid swimming with open cuts, and to avoid swimming if they are pregnant or if they have a weakened immune system.
The advisory is in place for both beaches over the weekend until Monday.
Galway City Council said that higher levels of bacteria are usually short-lived and most bathers are unlikely to experience any illness.