Temperatures in Austin are expected to hit 34°C during Saturday’s sprint race, exceeding the FIA’s 31°C threshold for a heat alert. Sunday’s grand prix is forecast to reach around 31°C.

Under the regulations introduced this year, teams must either fit cooling vests to their drivers or add a 0.5kg ballast to the car if the system isn’t used.

The same rule applied at the Singapore Grand Prix, where F1’s first-ever heat hazard was declared.

Drivers had mixed reactions to the cooling vests, with Ferrari’s Charles Leclerc telling Speedcafe they worked for about five laps, while Fernando Alonso reported comfort for roughly the first hour of the race.

Sauber rookie Gabriel Bortoleto said he wasn’t as challenged by the heat as expected.

“It was physical, but I was expecting more if I’m honest,” he said.

“I turned [the vest] on for the first 10-15 laps and then after that it gets quite hot, so it’s better to turn it off.”

Red Bull’s Max Verstappen voiced his frustration with the mandatory consideration of the vest, saying in Singapore that it “needs to be a driver choice.”

He added: “I don’t like the tubes that are on you, on your body, with the belts that go next to you.”

Others, like Esteban Ocon, believe the vests should remain an option for safety reasons.

“At some point one driver is going to be coming back from a cold or having a cold in the weekend and he might lose consciousness with how much dehydration we can get,” he told Speedcafe.

“I think for safety it is worth putting it. If it’s fine I’m happy to have a bit more comfort as well.”

The FIA plans to meet with drivers later this year to review the cooling vest regulations and share medical data supporting their use.

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