Explained: What the weighty issue of the FIA heat hazard means for Singapore GP

The FIA has issued its first-ever heat hazard warning ahead of round 18 of the F1 2025 season, the Singapore Grand Prix, with the heat index forecast at greater than 31°C.

The drivers now have the choice of wearing a cooling vest while in the car, or their F1 machinery being fitted with extra ballast.

FIA: A heat hazard is declared

“In accordance with Article 26.19 of the Sporting Regulations,” read the brief statement from motorsport’s governing body ahead of the Singapore Grand Prix, “having received a forecast from the Official Weather Service predicting that the Heat Index will be greater than 31.0 °C at some time during the race at this event, a Heat Hazard is declared.”

Following a swelteringly hot and humid Qatar Grand Prix in 2023 when several drivers were severely affected by the extreme heat, the FIA explored technology to create a cooling vest for the drivers to wear inside the cars.

Logan Sargeant retired from the race having suffered intense dehydration, while his Williams teammate Alex Albon was also unwell, Esteban Ocon vomited in his helmet and Lance Stroll worryingly revealed he had passed out in the car.

“It’s ridiculous,” Stroll said. “These temperatures, everything goes blurry. The last 25-30 laps it’s just blurry in the high-speed corners. Blood pressure dropping, just passing out, basically, in the high-speed corners with high loaded G-forces.”

A cooling vest made from new wearable-tech shirts using several metres of tubes to pump cooled fluid around the upper body was subsequently designed for the drivers but it was met with mixed reviews in Saudi Arabia this year where the air temperature hit 34°C.

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“No, is the answer,” said Oscar Piastri. “I think it still has a bit of fine tuning to go. For me personally, it’s not quite ready to be used.”

His big issue? The weight of the vest. “If you want to use it, it will come with a weight penalty on Sunday,” explained the McLaren driver.

Ocon raised another concern as he explained that it is “much more bulky and a lot bigger, we would need to basically redo a complete seat and I’m not even sure that doing that would still be suitable in corners.”

But five months on with the FIA issuing its first-ever heat hazard warning, the drivers now have a choice – they can wear the vest and carry the extra weight, or they can choose not to but they will have to carry extra ballast in their cars to balance against those opting for the vest.

Article 26.19 of the FIA sporting regulations states: “Any driver may elect not to wear any items of personal equipment that form part of the driver cooling system.

“In such circumstance, all other components, including any cooling medium, of the Driver Cooling System must be fitted.

“In addition, the difference in mass between the driver’s personal equipment normally used and any items of a driver’s personal equipment that form part of the system must be compensated by the fitting of 0.5kg of ballast in the cockpit, such ballast designated for this purpose will be included in sum of masses described in Article 4.7b of the Technical Regulations.”

According to reports, that could be as much as 5kg minimum weight for the race.

George Russell, who used the vest in Bahrain, believes it is worth it to rather wear the vest.

“Every car is also different, every cockpit runs at different temperatures,” he said. “I know we’ve seen our cockpit getting up to 60 degrees before, and the heat hazard is at 31 degrees.

“When you compound that with the sunlight and the temperature of the cockpit, it is like a sauna in the race car.”

“Somebody made the point recently, like football players on a cold day, some people are wearing gloves, some people have got short-sleeved shirts on, and that should be the driver’s choice. Maybe the heat hazard should be reduced slightly because we’ve not yet gone over it. Maybe it could be adjusted by a few degrees.”

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