The heat is on Sebastian Vettel at this weekend's Malaysian Grand Prix.

After blowing pole position by causing a crash at the Singapore GP two weeks ago, the Ferrari driver threw away a golden chance to regain the championship lead from Lewis Hamilton.

Instead, he drifted 28 points behind the British driver, who clinched his sixth win of the season for Mercedes.

"The last race was a strong reminder that sport always has the power to surprise," Mercedes head of motorsport Toto Wolff said.

"We have been on the receiving end of those bad moments before."

But with just six races remaining, Mercedes has the upper hand and Vettel's margin for error is increasingly small.

He can ill afford another blip in Malaysia, where the intense heat and stifling humidity make it one of Formula One's toughest races.

Singapore offered some respite, since it was a night race, but this one is raced in afternoon heat with 80 per cent humidity. Cockpit temperatures reach around 50 Celsius.

"It's like being in a sauna. We have all of our gear on and the car is hot as well," Mercedes driver Valtteri Bottas said.

"The seat itself is warm, and then we're surrounded in the cockpit by the electrical boxes."

Drivers can expect to shed five per cent of their body weight in fluid loss.

"Fatigue sets in," Bottas added. "It's more difficult to be consistent and, in the very worst cases, you can develop cramps or even problems with your vision."

The undulating, 5.5km track - a mixture of long straights and quick, sweeping corners - is also one of the most challenging, and enjoyable, for drivers and many are sad that the Sepang International circuit is hosting its final race.