SpaceX isn't saying why, but it's postponing the launch of a secret government payload called Zuma for 24 hours.
A two-hour launch window for the Falcon 9 rocket is now scheduled for Friday night at 8:00 from Cape Canaveral Air Force Station.
Temperatures will be in the 40s, but the Air Force says there's a 90 percent chance of acceptable conditions for liftoff.
SpaceX plans to return the Falcon 9's first stage to Cape Canaveral and people in east Central Florida are likely to hear sonic booms.