All systems remain "go" for Tuesday night's attempt to launch a United Launch Alliance Atlas V rocket.
The rocket is carrying a next-generation satellite designed to improve communications for U.S. ground forces around the globe, called the Mobile User Objective System, or MUOS for short.
It will provide 10 times more capability than current systems in use, including voice, video and data.
The satellite for the U.S. Navy will join two previous upgraded ones launched in 2012 and 2013.
Forecasters said there is a 30 percent chance thick clouds could violate launch constraints.
The rocket is set to lift off from Launch Complex 41 at Cape Canaveral Air Force Station. The window runs from 7:42 p.m. to 8:26 p.m.
If the launch is scrubbed, there is a 30 percent chance cumulus clouds could violate launch constraints for Wednesday's attempt.