TAMPA, Fla. (WFLA) — NASA will not launch its SpaceX Crew-3 mission from the Kennedy Space Center this weekend and is instead considering bringing the astronauts from Crew-2 back to Earth before launching the new crew.

The Crew-3 mission was initially supposed to launch on Halloween, but that had to be delayed due to poor weather conditions. NASA pushed the launch back again earlier this week because a crew member had a “minor medical issue” not related to COVID-19. As of Thursday, NASA says that medical issue is still being monitored but is “expected to be clear prior to launch.”

When the second delay happened, it was announced that the earliest possible launch opportunity would be late Saturday, Nov. 6. But according to a new update from NASA, that won’t be happening because weather conditions don’t appear favorable this weekend.

“Weather officials with the 45th Weather Squadron forecast only a 40% chance of favorable launch weather on Saturday, Nov. 6, with the primary concerns revolving around liftoff winds, cumulus clouds, and surface electric field constraints,” the agency said. “The down range weather also is not acceptable on Sunday, Nov. 7 due to risks associated with launch abort sites up the eastern seaboard.”

The space agency now says it is reviewing launch opportunities for Crew-3, as well as return opportunities for Crew-2, and will not launch a mission this weekend.

“Mission teams now are considering whether to return the agency’s SpaceX Crew-2 mission from the space station ahead of launching the next crew rotation due to the associated weather considerations for both launch and recovery operations,” NASA said in a blog post on Thursday.

NASA and SpaceX launched the Crew-2 mission, carrying four astronauts to the International Space Station, in April. After more than six months in orbit, that crew is getting ready to come home.

The earliest opportunity for Crew-2 to undock from the International Space Station is 1:05 p.m. EST on Sunday. There’s also a back-up opportunity to undock on Monday. The undocking begins the astronauts’ return trip to Earth and eventual splashdown off Florida’s coast.

If NASA decides not to begin the Crew-2 return process on Sunday or Monday, the earliest launch opportunity for Crew-3 would be 9:15 p.m. Monday. NASA noted that mission teams are still monitoring weather conditions that day and have concerns about strong winds at the launch pad and unfavorable conditions down range.

“Mission teams will make a final decision on whether to prioritize Crew-3’s launch or Crew-2’s return in the coming days based on the likelihood of favorable conditions for a Crew Dragon splashdown or Crew Dragon launch,” NASA said. “NASA and SpaceX also are reviewing the time needed between launch or return operations.”

“These are dynamic and complex decisions that change day by day,” Commercial Crew Program Manager Steve Stich said. “The weather in November can be especially challenging, so our goal is to move forward on the plan with the highest probability of mission assurance and crew safety.”

When it launches, Crew-3 will carry NASA astronauts Raja Chari, Tom Marshburn and Kayla Barron, along with European Space Agency astronaut Matthias Maurer, to the International Space Station. The crew will stay there for six months.

The Crew-2 return will bring NASA astronauts Shane Kimbrough and Megan McArthur, Japanese Aerospace Exploration Agency astronaut Akihiko Hoshide and European Space Agency astronaut Thomas Pesquet home.