"This is as real as it gets," the NWS tweeted in all capital letters Friday. "Nowhere in the Florida Keys will be safe."
The powerful storm, which barreled through a number of Caribbean islands earlier in the week, had left at least 20 people dead as of Friday evening.
Irma is expected to make landfall in Florida, prompting mass evacuations in the state. According to the National Weather Service, Irma is expected to be "catastrophic, life-threatening wind and storm surge impacts" in the Florida Keys on Saturday night and Sunday. The service reminded Florida Keys residents that there is still time to leave the area before the storm arrives.
Ed Rappaport, the acting director of the National Hurricane Center, said the Florida Keys will particularly feel the hurricane's impact, and could receive at least five to 10 feet of storm surge, along with destructive waves.
"It's not clear that it's a survivable situation for anybody that is still there in the Keys," he told WSVN.