Hawaii was the summer poster child of what a U.S. travel rebound could look like, but now it's quickly turning into what could be a nightmare fall.

As Hawaii's Lieutenant Governor Josh Green explained to Yahoo Finance Thursday, a 14-fold spike in COVID-19 infections since July and a surge in hospitalizations has led the Aloha state to "hit the pause button on travel to Hawaii until October."

"As a physician, I'm seeing the impact on our hospitals. Our hospitals are now full in the state of Hawaii because we've had a large surge since July 4," Green said. "And when I say full, I mean so full with COVID patients that we don't have any access to transfer other patients, like heart attack patients and stroke patients that I see in the hospital, because we don't have ICU beds."

Hawaii's huge step backwards is particularly surprising given how stringent testing requirements for travelers basically eradicated COVID on the island earlier this year. It's also surprising given Hawaii's vaccination status. About 66% of Hawaii's adult population is fully vaccinated, and a nation-leading 87% of its adult population has received at least one dose.

The state only recorded about 50 cases a day in July, when the state opted to lift its requirement for U.S. travelers to show a negative test before traveling to the islands as long as they were vaccinated. But now, as the state averages more than 700 daily cases, Green explains federal travel guidelines are complicating a return to stricter controls at the state level.

"We now have to wrestle with the fact that the CDC and the FDA have given us formal recommendations that people can travel safely if they are fully vaccinated. That creates some legal challenges," he said. "I will say this, there is still a concern that people will catch and spread the Delta variant even if they are fully vaccinated."

As such, Gov. David Ige (D, Hawaii) stopped short of either requiring testing for travelers or officially restricting travel from other states, however, Green did note renewed capacity restraints on the island could force travelers to reconsider. Earlier in August, for example, the state limited indoor capacity in restaurants, bars, and gyms to 50%.

"It will be a little more difficult to get a restaurant reservation. No one is allowed to gather indoors with groups larger than 10, or outdoors in groups larger than 25. That means that a lot of the activities that people tend to do in Hawaii are severely restricted," Green said.