With temperatures predicted to exceed 31 degrees C this weekend, the FIA has declared the Singapore event to be a heat hazard.

"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," announced the sport's governing body on Thursday.

This protocol was introduced following the 2023 Qatar Grand Prix when a number of drivers required medical treatment due to the heat and dehydration.

Now, at designated events cars must be fitted with a Driver Cooling System which includes pumps, a coolant reservoir and heat exchanger which feed coolant through a special vest that the drivers wear beneath their overalls.

While it was initially intended to be mandatory that the vest be worn, after drivers complained of being uncomfortable it was declared optional. However, those drivers who opt not to wear the vest must have 0.5kg of ballast added to their car in order to maintain the same overall minimum car weight as those that wear them. Whether the driver wear the vests or not, all cars must be fitted with the equipment that powers them.

"We've used the driver cooling vest a few times already this season at the hot races," said George Russell who gave the vest its debut in Bahrain. "Obviously, this is the first time where it's become mandatory, which I think is good news.

"Not everybody finds the top comfortable," he admitted, "but I think some find it more comfortable than others. And of course, over time, you'll be able to adjust it to your own preferences.

"The concept is good. When you're racing in 90% humidity and the cockpits are getting on for 60 degrees, it's a bit of a sauna inside the car. So I think we all welcome it."

"We now have the choice to run the cooling vest, which is something we'll consider and keep in mind throughout free practices in case it's way too warm in the car," added Charles Leclerc. "I don't expect this weekend to be harder than last year, and last year was very warm and very tough, but it was still doable. It's something I will keep in mind for sure."

"I think it's a nice thing that we've got a choice at least to use this cooling vest or not," said Alex Albon. "Different teams have different solutions, and within the cooling vest itself there are different ways to make it work.

"I don't see it as a bad thing-and I think it's safe," he added. "It's a good thing; it's another step forward in terms of making all drivers comfortable. It's likely I'll be using it for this weekend.

"As a team, Williams, we started using it early last year, experimenting, so I think we've got a good grasp of how to make it efficient and work for us and make it comfortable. In terms of preparation, it's not like I'm taking the cooling vest in the sauna with me-still preparing like normal. I work a bit more than maybe other drivers on it just because I feel the heat quite a lot."