SpaceX postponed until Thursday a launch to propel a communications satellite into a distant orbit, followed by another attempt to guide the Falcon 9's first stage to land on an ocean platform.
"Team opting to hold launch for today. Looking to try again tomorrow," SpaceX said on Twitter.
"Window also opens at 6:46 pm (2346 GMT). Rocket and spacecraft remain healthy."
The weather for Wednesday evening was only 60 percent favorable, with thick clouds over Cape Canaveral, Florida, where the launch pad is located.
The goal of the launch is to send a Boeing-built SES-9 satellite—delivering television and high-speed broadband to the Asia-Pacific region—to a geostationary transfer orbit (GTO) far above the equator.
But SpaceX is also trying to hone its landing technique on a floating platform, known as a drone ship, in order to one day recycle rocket parts, making spaceflight less expensive and more sustainable.
Several attempts at water landings have already failed, but SpaceX was able to successfully land the tall, gleaming white portion of the rocket on solid ground back in December.
The California-based company headed by Elon Musk cautioned this week that a successful landing was "not expected."
© 2016 AFP