The storm dumped rain on parts of Puerto Rico and the Dominican Republic and took aim for the Bahamas. More than 17,000 people in Puerto Rico were without power and about 5,000 without water.
Cristobal is expected to move slowly over the next 36 to 48 hours, raising risks of heavy rainfall totals in its path.
The storm is expected to miss hitting the U.S. coast, though it may produce strong swells.
"Even if a tropical storm or hurricane was to stay east of the Atlantic coast of the U.S., a strong system would generate swells that propagate outward that could reach the shoreline in the form of rough surf and strong rip currents during the last week of August," AccuWeather.com Senior Meteorologist Alex Sosnowski said.