Formula 1 has declared the Singapore Grand Prix a heat-hazard race, the fourth time the designation has been used this season and the second race weekend in a row. The status applies when temperatures are forecast to exceed 31C at some point during a race and permits teams to fit cooling devices to their cars. The Singapore Grand Prix first joined the F1 calendar in 2008, while the heat-hazard classification was introduced in 2025.

The race is also being held amid air-quality concerns linked to smog from fires in Indonesia. F1 is monitoring the situation, which also affected last weekend’s Bahrain Grand Prix in Malaysia, but does not currently consider it a major concern. The source report referred to the event as the Bahrain Grand Prix in Malaysia.

Singapore is near the equator and is regarded as one of the most demanding venues for drivers. George Russell and Lewis Hamilton were treated for heat exhaustion after the 2024 race. Temperatures in the city are typically between 31C and 33C throughout the race weekend, with high humidity and a chance of rain each day. Although the race takes place at night, temperatures remain around 30C after dark.

A cooling kit is optional. Drivers who choose not to use one must carry 5 kilograms of ballast in their car, a measure intended to ensure they receive no competitive advantage from opting out. The system typically uses a cooling tank and pump in the car’s nose to circulate chilled liquid, such as glycol, through pipes in a fireproof top worn beneath the driver’s overalls.

Some teams and drivers have avoided the equipment because of two practical problems. It can be difficult to keep the liquid cool long enough for an entire race, a particular challenge in Singapore because it is the longest race of the year. Some drivers also find the cooling top uncomfortable in the cockpit’s confined space. If the liquid warms up, it can reach the car’s temperature, which is considerably above the temperature outside. Cockpit temperatures in F1 can exceed 40C.

Mercedes is among the teams that chose not to run the system, preferring to direct the resources needed to make it reliable for a full race toward car performance. The governing body, the FIA, has allowed teams to claim $50,000, or £38,000, under the cost cap if they develop a system that keeps the liquid cool throughout a grand prix. A further $75,000, or £57,000, is available if they can make the top comfortable.

Mercedes deputy team principal Bradley Lord called the allowance “small.” He said: “We didn't believe that allowance was sufficient for us to be able to develop a solution that would be robust enough to last for the entire race.”

Singapore follows the Austrian and Italian races, as well as last weekend’s Bahrain Grand Prix in Malaysia, in receiving the heat-hazard designation this year. The Austrian and Italian events took place during a Europe-wide heatwave that produced record temperatures across the continent. Typical temperatures in Malaysia and Singapore are comparable to those elsewhere in south-east Asia. The report said those races would have met the heat-hazard criteria numerous times in the past if the designation had existed before 2025.

The Singapore Grand Prix’s night schedule does not remove the heat challenge for drivers, and teams must weigh the cooling system’s potential benefit against its comfort and reliability limits. The weather forecast threshold, optional equipment rules and ballast requirement all form part of the official designation’s operating conditions.

Based on reporting by BBC Sport.