A planned Tuesday launch attempt for the Artemis One rocket will not happen due to Tropical Storm Ian.
NASA made the announcement Saturday morning, telling its crews to "stand down" at Kennedy Space Center in Florida.
A forecast released by US Space Force had put weather conditions brewing in the Caribbean at only 20 percent favorable for a launch.
A decision on whether to roll back the space launch system rocket and Orion spacecraft off the launchpad to the vehicle assembly building has not yet been made.
Tuesday would have been the third launch attempt of the rocket.
NASA in a release says it will continue to monitor conditions before making the call to schedule another launch.
NASA officials are eager to launch the Space Launch System rocket for the first time, which would mark the first major step in its Artemis I program to return astronauts to the moon. This launch would have no astronauts on board and is seen as a test of the vehicle before the space agency flies humans.
If all goes well, NASA would send four astronauts in Orion to orbit the moon as soon as 2024, with a landing on the moon’s surface to come a year or two later.