Preparations continue at the Kennedy Space Center for a Falcon 9 launch on Thursday.
The launch window extends from 9:50 a.m. to 2:55 p.m. EDT.
The forecast from the 45th Weather Squadron at Patrick Air Force Base predicts a 50-50 chance of acceptable conditions during the launch window, with better odds expected during the morning. Clouds are the main concern.
Hurricane Irma is not a factor in the launch weather forecast.
The SpaceX Falcon 9 will be carrying the Air Force's X-37B winged Orbital Test Vehicle into low Earth orbit. This will be the program's fifth mission and the third trip into space for this particular vehicle.
The Falcon 9 first stage is scheduled to make an attempt to return to the launch site, touching down at Landing Zone One at Cape Canaveral Air Force Station about eights minutes or so after liftoff.
WMMB will provide live countdown updates throughout the window.