Sandbags were put out in Clontarf, while the car parks along the promenades in both suburbs were closed.
Dublin City Council also closed the flood gates on the River Dodder for the weekend and increased defences on the River Tolka.
The flood defences on the Liffey Boardwalk were closed, as were those at Spencer Dock.
"It is one of the highest tides of the year and other factors involved might push it higher," Met Eireann forecaster John Eagleton told the Herald.
"You have strong onshore winds from the south east, then you have rain, and it's the middle of winter, so the rivers are a bit higher and the pressure is dropping.
"All of these factors, if they align in the wrong way, you can get serious flooding," Mr Eagleton said.
City official Pat Cronin said the council's flooding advisory group met and carried out detailed risk assessments based on information from Met Eireann on pressure, wind speed and rainfall. The council's 6am assessment this morning indicated the capital was going to get a "surge of about 600mm at high tide today", Mr Cronin said.
The figures were broadly in line with the predictions made earlier in the week.
"We have our defences in place to cope with that surge," he said.
Rainfall today was not a factor as only 2mm fell between midnight and 7.30am today.
Some wave overtopping was expected in Sandymount along the promenade and as a precautionary measure the council closed off Marine Drive after this morning's rush-hour.
High tide in Dublin today is at midday.
Mr Eagleton said, despite the flood warnings today, it "will be a good weekend to be out and about". It is forecast to be cold but the frost will not linger for the day, he added.
Met Eireann's flood warning was issued as a result of high tides, onshore gales and up to 25mm of rain. In Cork city this morning, the threat passed but the east of the country was on alert until midday.
Flood waters rose on several streets in Cork City centre, without entering buildings. The flooding then receded and the tide turned.
Met Eireann says tomorrow will be bright and mainly dry.
Highest temperatures will range from six or seven degrees.