Here are some of the best images of Hurricane Florence by Gerst and Ricky Arnold, a fellow NASA astronaut living aboard the ISS.
The hurricane is expected to reach the coastlines of North Carolina and SC on Friday morning, with experts estimating that it will continue to grow in strength.
"Watch out, America!" Gerst, who joined the crew of the International Space Station in June, said Wednesday in a tweet featuring pictures he took of Hurricane Florence. Packing heavy winds with a maximum sustained wind speed of 130 miles per hour (195 km/h), the hurricane is slowly barreling toward the U.S. East Coast, at a speed of approximately 13 miles per hour (20 km/h).
According to NASA, this footage of Hurricane Florence was captured by astronaut Ricky Arnold on the the International Space Station at 8:10 am ET on September 10.
In fact, Gerst wrote on Twitter that Hurricane Florence is "so enormous" it could only fit in the frame of a wide-angle camera.
"This is a no-kidding nightmare coming for you", he added.
The weather agency also warned "life-threatening freshwater flooding is likely from a prolonged and exceptionally heavy rainfall event". Arnold shared his first photos of Hurricane Florence, taken when it was still a Category 2 storm.
At around 12 p.m. EDT (1600 GMT), the National Hurricane Center (NHC) announced that Hurricane Florence had strengthened to a Category 4 storm. "It's chilling, even from space", Gerst tweeted earlier today.
From the International Space Station, Alexander Gerst warns the East Coast to get ready for Hurricane Florence in this photo posted to Twitter on September 12, 2018: "This is a no-kidding nightmare coming for you".
"I have just been informed that this is one of the worst hurricanes that came to the East coast for many years".