Race Director Rui Marques said temperatures in excess of 31 degrees Celsius (88 degrees Fahrenheit) had been forecast.
Declaring a heat hazard requires teams to fit a driver cooling system, such as a liquid-cooled vest, though drivers are not obliged to use them and can take a ballast penalty instead.
The car's minimum weight is increased to accommodate the hardware.
Last October's Singapore Grand Prix was the first time the heat hazard designation had been applied after it was added to the rules in 2025, followed by the US Grand Prix in Austin, Texas, the same month.
"I think the moments where you have zero kph in the car, they are definitely the worst," said Red Bull driver Isack Hadjar of sitting on the starting grid in such hot conditions.
"To be fair, when driving, it’s not too bad. We’ve got good AC (air conditioning) with our open cockpit, so it’s fine."
The Frenchman said he would not be wearing a cooling vest because his felt too uncomfortable and cumbersome.
"It works really well, though, for like 10 minutes, and then it’s warm again. So, I’m okay. Honestly, I’ve never been to a point where I really needed that vest. If I need it, that means the car as well can’t handle it, and we can’t drive. So, I think the car will give up before I do," he said.
McLaren's Oscar Piastri was more positive and revealed - when asked if he had acclimatised in a sauna - that he had prepared for the heat with portable heaters and an exercise bike in a small bathroom.
"You can cause yourself a lot of discomfort, a lot of pain by doing that. So, I do that for the benefit of my performance. Not for pleasure, that’s for sure," smiled the Australian.
"I think if you get the (cooling jacket) system working well, then it can help a bit. It’s not a complete game changer, but when I used it last year, it was okay."
Sunday's race will be the eighth round of the championship, with 19-year-old Mercedes driver Kimi Antonelli at the top of the standings.