Formula 1 declares heat hazard ahead of United States Grand Prix

On Thursday, at COTA, FIA-appointed Formula 1 race director, Rui Marques, said in a statement sent to teams that an official forecast predicted the heat index would be more than 31 degrees Celsius (87.8°F) at some time during the Saturday' Sprint Race or Sunday's Grand Prix.

The regulation was invoked for the first time at this month's Singapore Grand Prix due to the high temperatures and humidity encountered at Marina Bay.

The regulation was brought in after Formula 1 drivers suffered exhaustion in the 2023 Qatar Grand Prix and means drivers can either wear a cooling vest, which circulates cold liquid through tubes to maintain body temperature, or add extra ballast to their cars.

The cooling vests are set to become mandatory in hot conditions from next season but are not universally popular, with some drivers preferring not to use them.

"I haven't used the vest. I'm also not intending to use it because I feel like this needs to be a driver choice," Red Bull's four-times Formula 1 world champion Max Verstappen said in Singapore.