USGP preview: Lewis Hamilton gunning for a third Stetson but will rain ruin his race?

If Lewis Hamilton wins the US Grand Prix in Austin on Sunday, with Nico Rosberg second and Sebastian Vettel third, a result that has already occurred on four occasions so far this season, Hamilton will win the Formula 1 world championship with three races to spare.

However, heavy rain at the Circuit of the America’s is forecast for much of the weekend and a wet race could occur for the first time in the circuit’s F1 history, as low temperatures and pressures in the west meet with moisture coming from the Gulf of Mexico, according to Ubimet, the official weather service provider of the FIA.

When the World Endurance Championship visited the Texan track in 2014, a heavy thunderstorm broke two hours into the race and forced a 50-minute suspension after several cars skated off the circuit.

Ubimet predicts that both Friday practice sessions will be wet and unsettled weather will remain throughout Saturday.

Ubimet’s chief F1 meteorologist, Steffen Dietz, said: “During [Saturday] afternoon some further, but weaker showers are still expected, so the starting grid could easily be jumbled by the rain too."

Two heavy rain showers have been predicted for Sunday and at least one is expected to hit the track during the Grand Prix. However, “their intensity should not be comparable to the amounts of the two previous days,” according to Ubimet’s report.

Assuming he survives the wet weather, Hamilton can clinch his third F1 world title if he outscores Vettel by nine points and Rosberg by two.

The USA has been the scene of six previous title deciders, in 1959, 1970, 1974, 1977, 1981 and 1982 – with the most recent occasion the year Keke Rosberg, Nico’s father, won his only F1 championship.

If he does claim the 2015 title on Sunday, Hamilton will become Briton’s second three-time world champion, after Sir Jackie Stewart, but will be the first British driver ever to secure back-to-back F1 championships.

Speaking ahead of the race in Texas, Hamilton explained that despite his 66-point lead, he would not be changing his approach and is not taking the title for granted.

He said: “Austin is definitely one of the highlights of the year for me. I love the States and spend a lot of time over there, so it’s a weekend I always look forward to.

“I’ve learned from experience that nothing is ever done until it’s done in this sport, so I won’t be taking anything for granted going into the weekend. I’m going into this next race with the same approach I’ve had all year. There are four races left for me to get this Championship tied up and as long as it’s done by the time I cross the line in Abu Dhabi that’s what really counts.

“I’m excited to get out there, give my best and if I can come away with a third Stetson hat that would be unbelievable."

Mercedes, which wrapped up the constructors’ championship last time out in Russia, can secure its 50th pole position this weekend if one of its drivers comes out on top during qualifying in Austin.

The German marque can also claim its 25th 1-2 finish this weekend, a result that it likely lost in Sochi after Rosberg suffered a throttle pedal failure.

After that incident, which forced Rosberg out of the race, Mercedes’ technical boss, Paddy Lowe, explained that his team would be working hard to avoid a repeat event this weekend.

He said: “Nico’s retirement unfortunately prevented what looked a likely 1-2 finish. As a result, his push for the Drivers’ Championship now looks to be a tough task – but you can never give up in this business and we know Nico certainly won’t be doing so.

“At the same time, we go to Austin with the potential to secure that title with Lewis, who has been in superb form. It’s up to us to provide both drivers with the tools they need to close out a successful end to the campaign.