SpaceX must consider a few factors before Starship can be launched.
The weather is always a good start.
On Sunday, the company announced that it was already tracking wind shears which could make it unsafe to fly. In the early morning hours of Monday, the company launched a weather balloon near the launch site on South Padre Island.
Even if the weather is perfect, there are still a few things that could derail a launch.
All morning, engineers on the ground are monitoring the data from the rocket. Scrubs could be triggered by any blips, or issues that are identified.
Even if it is the last few seconds before takeoff, the onboard computer could detect this and stop everything.
Elon Musk, CEO of SpaceX, also addressed scrubs at a Twitter Spaces Event on Sunday night: "There is a good possibility that this launch will be postponed because we are going to take great care with this launch."