Ahead of today's opening session the air temperature is 29.1 degrees C, while the track temperature is 55.1 degrees. It is bright, sunny and hot but that is unlikely to be the case all weekend.

In terms of updates Mercedes has a new halo, rear wing and beam wing, while Red Bull only has a new beam wing.

McLaren has new front brake cooling and a new diffuser, while Alpine has a new beam win.

AlphaTauri has a new rear wing endplate, Aston Martin a new rear wing and Alfa Romeo a new floor.

And while Ferrari and Williams have no updates, Haas finally has its much-anticipated package which includes a new floor, engine cover, cooling louvres, rear suspension and rear brake winglets. However, this weekend it is only available to Magnussen.

At Alfa Romeo, Robert Kubica replaces Valtteri Bottas in this session.

The lights go green, and Vettel leads the way. He is followed by Stroll, Perez, Norris, Kubica, Zhou and Magnussen. As more drivers head out all three compounds are in use.

Vettel gets things underway with a 42.443 but this is instantly eclipsed when Stroll crosses the line at 33.123.

Just moments into the session all twenty drivers are on track, no doubt mindful of the conditions we are expecting over the rest of the weekend. It is likely to be very wet on Saturday, with mixed conditions on Sunday.

Of the first wave, Verstappen goes quickest (21.235), ahead of Sainz, Ricciardo, Ocon and Albon.

Russell complains of a strange noise from his power unit, almost like a "whistling sound".

Magnussen goes eighth (25.046) in the updated Haas, while teammate Schumacher is ninth (25.212).

A 20.696 sees Sainz go top, while Ricciardo goes second with a 20.796.

Leclerc goes quickest with a 20.225, just 0.018as up on Verstappen.

The leading three - Leclerc, Verstappen and Sainz - are on softs, while Ricciardo, Ocon and Albon are on mediums. Hamilton (seventh) is the highest placed hard runner.

Hamilton improves to sixth with a 22.112 as - after 14 minutes - Perez and Norris are the only drivers yet to post a time.

Sainz goes quickest with a 20.184, as Perez (softs) finally gets his name on the timesheet, stopping the clock at 21.053 to go fifth.

Leclerc retakes the top spot with a 19.863, while Verstappen responds with a 18.872, just 0.009s between the pair.

As Sainz posts a 19.671, Perez improves to fourth (20.211), ahead of Ricciardo, Ocon, Russell, Hamilton, Albon and Alonso.

Verstappen and the Ferrari pair continue to trade fastest times, while Norris has yet to post a time.

Currently 7th and 8th, Russell and Hamilton head out on softs.

Well that's a new one... while on track, Perez sneezes several times. "Bless you," comes the call from his engineer. "A bit of an allergy around this place," says the Mexican.

On softs, Schumacher improves to sixth with a 21.027 but is demoted when Russell posts a 19.606 to go second and Hamilton a 19.710 to go fifth.

"Bit of bottoming into Turn 1," reports Russell.

As Magnussen heads out on softs, teammate Schumacher runs wide in Turn 3. The German is currently 12th (21.027) without the updates.

Surprisingly, Magnussen can only manage 15th (21.345), around 0.3s down on his teammate.

Hamilton runs wide in Turn 12 as Magnussen pits.

Having improves to 10th with a 20.695 Tsunoda subsequently locks-up and runs wide at Turn 1.

Norris finally posts a time, the McLaren driver going seventh with a 20.251.

As ever in the opening session, the Aston Martin pair avoid the softs like the plague.

"That was strange, big rear lock," reports Russell, as Magnussen improves to 13th with a 20.921. Nonetheless, he is only minimally quicker than his teammate.

Up front, Verstappen raises the bar with an 18.880, while PBs in all three sectors see Leclerc close to within 0.159s of the Dutchman.

Switching to the softs Stroll improves to 12th (20.580), while Vettel goes 11th with a 20.383.

Sainz retakes the top spot with an 18.750.

"What is it with them staying on the racing line," asks Schumacher of a very slow Leclerc.

Hamilton runs wide in Turn 7.

Now on softs, Norris improves to fourth with a 19.299, ahead of Russell, Perez, Hamilton and Ricciardo.

Having previously complained about Leclerc, now Schumacher is compromising Perez' lap. "He's on high fuel, it's a mixed bag out there at the moment," the Mexican is informed.

Looking to improve on 10th, Alonso runs wide in Turn 11.

The session ends. Sainz is quickest, ahead of Verstappen, Leclerc, Norris, Russell, Perez, Hamilton, Ricciardo, Ocon and Alonso.

Vettel is eleventh, ahead of Stroll, Gasly, Tsunoda, Zhou, Albon, Magnussen, Schumacher, Kubica and Latifi.

Check out our Friday gallery from the Hungaroring here.