Ahead of today's opening practice session, the air temperature is 26.1 degrees C, while the track temperature is 37.4 degrees. It is bright but there are some heavy, dark clouds in the distance. Rain is expected today - race control claims a 90% chance - but Saturday and Sunday are expected to be hot and sunny.

Though everyone is keenly anticipating the summer break, the battle for the title and midfield supremacy continues, with the updates coming thick and fast.

Mercedes, still hurting from last week's disaster, will be seeking to prove that it is a one-off, while Red Bull will want to continue where it left off and Ferrari needs to get a grip on reliability.

Usually notoriously hot, this weekend could be a struggle for Mercedes, while Charles Leclerc feels Ferrari will also not be as competitive as he would wish.

Racing Point, still high on that fourth for Lance Stroll, has another raft of updates as it aims to take the second half of the season by the scruff of the neck.

With Toto Wolff saying that a decision on Mercedes second driver should be made during the break, this is the time for a number of drivers to set out their stalls, it is also a time for others to get their acts together.

Kubica is first out, the Pole's fans set to outnumber those of Max Verstappen this weekend, followed by Hulkenberg, Norris, Perez and Sainz.

Indeed, with an eye on those clouds there is a flurry of activity.

As Hamilton makes an unusually early appearance, the first drops of rain begin to fall.

A mixture of softs and mediums, though Albon is on hards.

Three minutes in and all but Stroll and Verstappen are on track.

Kubica crosses the line at 30.942, but moments later Sainz posts 23.204 and Hamilton 20.763.

Leclerc goes second (20.871) and Vettel third (21.490), as Gasly sports the mother of aero sensors.

Hamilton improves to 19.961, but Leclerc responds with a 19.638.

"That shower was just the beginning of it," Hamilton is told, "we expect heavier rain in about four minutes."

"Box, box, box, box, we've seen a misfire," Bottas is told. The Finn obeys but it's a late call and the Finn, like teammate Hamilton last week, enters the pits on the wrong side of the pit entry bollard. The stewards are investigating.

A 19.953 sees Grosjean improve to second, ahead of Hamilton, Vettel, Magnussen and Kubica.

"I've still got this issue with the brakes," says Hamilton, "they're not in balance." His engineer doesn't agree, but the Briton insists.

Verstappen goes quickest with an 18.629, as Magnussen goes fourth (19.776).

What with Hamilton's brakes and Bottas' misfire, Mercedes weekend gets off to a difficult start.

That said, Hamilton improves with an 18.077 to go top.

Fifteen minutes in and there are 11 names on the timesheets, including all the big guns.

Back to back tests for Alfa where Raikkonen is running a high downforce rear wind and Giovinazzi low downforce. The Finn also has a sensor device on his air inbox.

"Tyres are gone," reports Leclerc after 11 laps on his softs.

Like Alfa, Ferrari is carrying out back-to-back tests, with Leclerc sporting a number of updates and Vettel still in Hockenheim-spec.

The rear of Raikkonen's car - or rather the left rear of the car - is smothered in flo-vis as the cameras pick up on the Finn beautifully catching a big slide.

"It's drizzling here, at Turn 5," reports Verstappen, as Stroll spins just ahead of him at the chicane.

Meanwhile, Hamilton consolidates his top spot with a 17.565.

Hulkenberg isn't happy with his car and is told to pit, nonetheless he is currently sixth and his teammate seventh.

"There's definitely something wrong with the car," reports Albon, "I'm going to box for flap adjust."

An 18.474 sees Gasly go third as teammate Verstappen spins in the final corner. The youngster spins the car the right way around, to the delight of the crowd. He is subsequently told it could have been due to the tailwind in that corner. "It's very sensitive on the rear," he says, losing a lot of grip in the last sector."

"In four to five minutes, we expect heavier rain," Sainz is told. At which point the people in the stands start putting on their rainwear.

As the rest pit, Leclerc heads out for one single lap on Inters.

Shortly after, Perez, Hulkenberg and Ricciardo head out on the green-banded rubber, gingerly feeling their way around.

At which point the sun breaks through and the rain stops. Now that's changeable. To add to the fun, there is a storm heading towards the track... and it aint wearing Haas overalls.

In the Ferrari garage, the mechanics appear to be fitting the updates to Vettel's car also.

Taking advantage of the changing conditions, Hamilton heads out on Inters. The teams are limited on Inters and Wets, so they have to be careful and not run them in too dry conditions.

"We will do a PU swap with Valtteri as a problem with the current unit has been identified," says Mercedes. "We are swapping in the other PU already in the pool. This will allow us more time to trace the problem outside the car."

At the point the extra set of tyres have to be handed back, it's: Hamilton, Verstappen, Gasly, Vettel, Leclerc, Magnussen, Perez, Hulkenberg, Sainz and Norris.

"Will we use these tyres again," asks Hamilton of the Inters. "Yes," he is told, "so look after them."

Sainz is told that the wind has reverted to being a cross-wind on the start/finish straight.

Hulkenberg (softs) goes third (18.469) having gone quickest in S1.

Moments later, Magnussen posts 18.369 on the softs.

Hamilton heads out on mediums, his time is only 0.233s off his best on the softs.

"Rear tyres temps are incredibly low after a hot lap," reports Hulkenberg.

Grosjean is unhappy - isn't he always - complaining that grip levels are like Monza. "There's an issue, an issue," he says, I've got everything, oversteer, understeer..."

As Perez spins in the same spot as his teammate earlier, Vettel (softs) goes quickest in S1. He loses a little pace in S2, while Hamilton goes quickest in exactly the same sector. The German goes second with a 17.399.

"I had a bit of traffic in the last sector," says the German.

Meanwhile, his Ferrari teammate reports that "the car doesn't feel great".

PBs in all three sectors see Gasly improve to fourth (17.682), as Norris goes eighth ahead of his McLaren teammate.

Shortly after his spin, Perez locks-up and runs wide in Turn 1.

"Box this lap, box this lap," Verstappen is told, "we've picked up some front wing damage on our first timed lap." The Dutchman having run wide in Turn 4.

Check out our Friday gallery from the Hungaroring, here.