A whole team of meteorologists is on hand from the 45th Space Wing and SpaceX to determine whether the weather will scrub the launch. As on Wednesday, the decision can be made right up to liftoff.
During the NASA broadcast on Wednesday, disappointment was evident as the weather team called it a no-go for launch.
Launch weather officers must be "clear and convinced" that no NASA "criteria are violated in order to give the weather GO call for launch," the 45th Space Wing Weather Squadron states.
For example, lightning in the area will cancel a flight, as will a cloud with a large enough electrical field to produce rocket-triggered lightning. This happens when a giant spark of electricity occurs when a large rocket flies through a strong enough atmospheric electric field.
The electric field needed to induce rocket-triggered lightning is much lower than for natural lightning.
"Either type of lightning could cause serious damage to the rocket and endanger public safety," the weather squadron states.
Forecasters also have to monitor the winds.
If there is a sustained wind of 30 mph or more at 162 feet above the launch pad, the mission will be canceled.
The weather squadron also has to monitor the weather downrange because if the Crew Dragon capsule encounters a problem, it needs to have a safe splashdown location.
Earlier this month, NASA had to delay its launch of the Atlas V rocket, US Space Force mission due to Tropical Storm Arthur. It launched the following day after the storm cleared out.