How air temperatures play a role in human spaceflight launches

Every rocket has weather constraints that it can safely launch within. These weather criteria include temperature, cloud cover, precipitation, liftoff winds and lightning. This is why launch providers like SpaceX monitor the forecast so closely in the time leading up to liftoff.

KENNEDY SPACE CENTER, Fla. – Arctic air has dropped temperatures across the U.S. in January 2024, bringing some of the coldest temperatures to NASA's Kennedy Space Center since SpaceX began launching commercial human spaceflights in 2020. 

SpaceX was set to launch four private astronauts as part of the Axiom Space Mission 3 (Ax-3) on Jan. 17; however, the launch was delayed to Jan. 18 at 4:49 p.m. ET when a Falcon 9 rocket will launch the four humans in the Crew Dragon spacecraft to the International Space Station

If the launch went as planned on the original launch date, it would have occurred during the coldest temperatures since SpaceX began launching humans more than three years ago. When the Space Shuttle Program ended in 2011, NASA paid Russia to launch American astronauts to the ISS until May 2020, when SpaceX began launching NASA astronauts under the space agency's Commercial Crew Program. 


A cold front moved in overnight Wednesday, dropping temperatures in Florida to near freezing in some areas of the Sunshine State and into the upper 40s for Central Florida. The National Weather Service office in Melbourne issued Wind Chill advisories for Central Florida through Wednesday morning that have since expired. 

Around 5 p.m. Wednesday, the FOX Forecast Center said the temperatures would be 54 degrees with winds between 10 and 15 mph and stronger gusts up to 20 mph. By Thursday, temperatures at Kennedy Space Center will be back in the 70s, closer to average for January. 

SpaceX has successfully launched 11 human missions to the ISS or orbital space for NASA and its international partners, Axiom Space and the private Inspiration4 mission. A review of National Weather Service data on those 11 launch dates shows Wednesday's launch could have been the first with temperatures in the 50s. With wind gusts up to 20 mph, temperatures could feel closer to 40 degrees. 

While 50 degrees sounds like a mild day to Florida's northern neighbors dealing with single-digit or negative temperatures, the chilly forecast is important for launching rockets.

Every rocket has weather constraints that it can safely launch within. These weather criteria include temperature, cloud cover, precipitation, liftoff winds and lightning

This is why launch providers like SpaceX monitor the forecast closely in the time leading up to liftoff. 


When asked about the cold forecast on a call with reporters, SpaceX Senior Director of Human Spaceflight Benji Reed said he couldn’t share the exact temperature constraints for SpaceX's Falcon 9 rocket but said they were monitoring the weather. 

"We want to ensure we can launch safely and with plenty of margin regardless of temperature, humidity, precipitation and wind and thunder and lightning," Reed said. "So we’re keeping an eye on it, and we’re watching the weather closely."

Coldest space shuttle launch turns deadly 

The Challenger disaster is the only deadly spaceflight in American history tied to the weather. It was a bitterly cold January day for Florida on launch day, with air temperatures at 36 degrees for the Jan. 28, 1986 launch. This was 15 degrees colder than any previous shuttle launch, according to NASA. 

The investigation into the Challenger explosion found that the loss was caused by a failure in the joint between two lower segments of a solid rocket motor. An O-ring seal returned to its uncompressed shape during the 36 degrees Fahrenheit weather, causing the joint to fail.

As a result, the space shuttle solid rocket motor booster seal and joint were redesigned to withstand all weather conditions for liftoff. There have also been developments in O-rings used on rocket boosters today that are designed with more temperature-hardy materials. 

Even with improvements in engineering and materials, temperature still plays a role in rocket launches today. 

NASA's Space Launch System rocket under the Artemis program cannot launch if the temperature at 132.5 feet is between 38 and 49 degrees Fahrenheit, depending on the wind and relative humidity. The rocket will not launch if temperatures are too hot, exceeding 94.5 degrees at 132.5 feet.