Liftoff had been scheduled for Thursday but because of unfavorable conditions along the Atlantic coast, it will now be set for 5:49 am (0949 GMT) Friday.
"For crewed missions we need to look downrange to make sure weather's good for a potential launch escape, and for recovery of the crew," acting NASA Administrator Steve Jurczyk told reporters.
The Crew-2 mission will carry four astronauts in the second routine taxi ride by SpaceX to ISS since the United States resumed crewed space flight, and the first with a European.
It involves US astronauts Shane Kimbrough and Megan McArthur, the Japan Aerospace Exploration Agency (JAXA)'s Akihiko Hoshide, and the European Space Agency (ESA)'s Thomas Pesquet, who is French.
The mission is also notable for being the first to use a previously used booster and a previously used capsule -- a key cost-saving goal of NASA's partnerships with private industry.
"(It is) really helping us to see the full capability and really realizing the dreams that we had when we started this effort, about 10 years ago with SpaceX," NASA's certification manager Tom Simon told AFP.
NASA's immediate goal is to be able to reuse booster rockets at least five times for human space flights.
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