The FIA have introduced a brand-new rule for the first time ahead of this weekend's Singapore Grand Prix.
F1 takes to the Marina Bay Street Circuit this weekend as the 2025 season begins to reach its closing stages.
Red Bull's Max Verstappen has won the last two races, including the most recent Azerbaijan Grand Prix, with McLaren enduring a nightmare weekend in Baku.
Championship leader Oscar Piastri crashed out in qualifying, before then jumping the start on race day and crashing again on lap one, causing him to retire.
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McLaren team-mate Lando Norris, who started the day 31 points behind Piastri in the standings, failed to fully capitalise on the Australian's horror weekend and could only finish in seventh, collecting six points.
Verstappen is now 69 points behind Piastri after his two consecutive wins, though there are only seven races remaining.
The drivers now head to Singapore knowing that the Grand Prix could be significantly disrupted by the weather - in more ways than one.
There is a risk of thunderstorms during the race on Sunday, with Singapore currently in the midst of its monsoon season.
But the heat can reach searing temperatures in the country, with Mercedes duo George Russell and Lewis Hamilton both suffering from what was described as 'borderline heatstroke' after last year's Grand Prix.
Footage aired on Netflix's Drive to Survive series showed Russell gasping for air in the paddock, with the Brit telling his partner that 'it was sixty degrees in there'.
Now, the FIA have declared an official heat hazard for the Grand Prix weekend, with temperatures set to pass 31 degrees.
It is the first time since a declaration has been made by the FIA, and is in response to growing driver and team concerns over recent years.
Their statement reads: "In accordance with Article 26.19 of the Sporting Regulations, 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."
What F1 teams and drivers must do after heat hazard declared
Ahead of this season, the FIA made a change to their regulations surrounding driver equipment.
They introduced a new wearable cooling vest, which features cooled liquid that is pumped around a series of tubes while drivers are in the car.
The vests were due to be made mandatory if temperatures were due to exceed 31°C during a Grand Prix, but there were complaints from some drivers after wearing them for the first time.
Instead, the cooling vests are now voluntary - but teams whose driver(s) does not wear it has to compensate by adding 0.5kg of ballast - extra weight - to the driver cockpit.
"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," the FIA regulation reads.
Ryan Smart