Ahead of today's opening session, the air temperature is 30 degrees C, while the track temperature is 47 degrees. It is warm, very warm.

In terms of upgrades. Ferrari has a new Front Wing and Rear Wing. While most upgrades this weekend are circuit specific, the front wing is not, indeed, its introduction is phased with the update of the articles 3.15.4 and 3.15.5 of the technical regulations, effective from this race onwards. In terms of the high downforce top rear wing, this is carried over from 2024 and was made available in Imola. Local flow features are improved, returning an efficient load increase.

Red Bull's Front Wing is also to comply with the revisions to the technical regulations. The front wing geometry has been revised to gain stiffness at minimal weight cost and then iterated to pursue the load characteristics sought.

Mercedes has new Floor Edge, Floor Fences and Rear Wing Performance. Additional vane elements and flap chord increase mass flow under forward floor, thereby increasing vorticity shed from the fence system, increasing floor load, while the new fence profile has improved local pressure distribution and position of vorticity, improving both local and downstream load through better onset flow. The rear wing is circuit specific, with increased camber aimed at gaining local downforce and drag along an efficiency slope appropriate for Barcelona.

Aston Martin has a new Front Wing which features revised tip detail between the front wing elements and the endplate. The main wing sections are also revised for compliance with TD018H. The revised tip detail improves the flow-field around the outboard end of the wing increasing the load generated in that area. Changes in section are for structural reasons.

The Alpines feature new Floor Fences and Floor Body. The floor fences have been optimised locally to improve the quality of the underfloor structures. This results in an improved flow delivery to the entire floor and generates local load. Meanwhile, local and subtle modifications have been done to the floor to maximise the effect of the updated fences and improve the flow-field quality.

Haas' new front wing, is another reaction to the he technical regulations updated to include more stringent FW flap deflection requirements. Consequently, a new FW construction was necessary to comply with these new requisites.

RB has a new Front Wing, Front Wing Endplate and Nose. The centre section of the front wing is loaded further relative to the outboard, modifying the downstream flow conditions. The update also addresses the increased stiffness requirements. The flow around the front wing tips is highly three-dimensional. The revised detail around the tips helps to reduce the losses created from this flow, while the nose tip drops down to meet the new FW sections, and the raised lower surface helps to increase the load generated by the centre section of the wing, which in turn modifies the downstream flow around the car field.

Williams has a new Front Wing, Rear Corner and Cooling Louvres. The combined geometric and construction changes to the front wing reduce the deflection to adhere to the latest regulations, while the geometric updates alter the flow pattern off the front wing and change the performance of both the front brake duct furniture and the forward floor. The revised exit geometry to the rear corner changes the flow rate through the brake duct and affects the brake cooling in a way that is suitable for the braking demands of this circuit. The update to the cooling louvres simply increases the flow through the radiators and therefore increases the PU cooling at the cost of downforce and drag. This will be the team's new maximum cooling setup, which may be of use here, but is more likely to be needed later in the season.

Stake has a new Floor Body, Coke/Engine Cover and Front Wing. The modifications to the floor body are targeted at improved flow field conditions for the underfloor from front to back, gaining some efficient and balanced downforce. On the engine cover the sidepod surfaces have been updated to adapt to the new floor developments and associated interactions, modifying floor top surface flow conditions. Finally, local front wing end plate developments are to improve outboard front wing performance and efficiency and also encourage better downstream flow quality.

McLaren, unsurprisingly, is the only team not to have brought any upgrades.

Victor Martins replaces Alex Albon in this session, while Ryo Hirakawa replaces Esteban Ocon at Haas.

The lights go green and Martins lead the way, followed by Lawson, Stroll, Hulkenberg and Leclerc. As more drivers emerge, most are on hards, though Stroll and Colapinto opt for mediums.

Stroll's 32.280 is soon eclipsed by Leclerc, Hamilton, Alonso and then Norris (16.095).

All bar Sainz are on track just minutes into the session.

Piastri goes second with a 16.104, as Russell reports that his steering feels "very light" as he's steering and "a bit weird".

An early trip through the gravel at Turn 10 for Hirakawa. "I'm sorry, sorry," he tells the team.

As ever, there are lots of aero rakes and flo-vis.

Alonso goes top with a 15.480, which is sure to please the partisan crowd.

"What the..., what was that," asks Lawson, as he is impeded by a Ferrari. Sporting a massive aero rake it is a mystery how the Ferrari didn't sport the Kiwi's approach.

Norris improves to 15.633 but remains second to Alonso as Verstappen goes third with a 15.805.

A 15.259 sees Norris go top.

On the mediums, Stroll is fifth and Colapinto thirteenth.

With 45 minutes remaining, Sainz has yet to appear.

Another incident involving a Ferrari and RB, as Hadjar appears to impede Hamilton.

Leclerc improves to fourth with a 15.775, while his teammate is eighth, ahead of Antonelli, Tsunoda and Gasly.

Sainz finally heads out and immediately goes seventeenth with a 17.112.

Twenty minutes in and there's a bit of a lull, certainly as the big guns are concerned.

Russell and Antonelli switch to the yellow-banded rubber, while Hulkenberg, currently 15th, switches to softs.

Russell crosses the line at 14.751, while his teammate stops the clock at 15.369 to go third.

Verstappen and Leclerc switch to softs as Hulkenberg goes second (14.865).

Hamilton and Tsunoda are on the red-banded rubber as the McLaren pair follow suit.

Leclerc goes top with a 14.238, as Sainz goes fourth (14.966) on the mediums.

PBs in all three sectors see Verstappen stop the clock at 14.085. Tsunoda goes third (14.643).

Hamilton goes second (14.096), but is demoted when Norris crosses the line at 13.718 having posted purples in all three sectors.

Piastri can only manage fifth, 0.576s off the pace.

Hadjar improves to sixth (14.294), ahead of Tsunoda, Russell, Hulkenberg and Sainz.

A 14.597 sees Bearman go sixth, while Gasly goes ninth (14.746).

Piastri improves to fifth, but remains 0.576s off his teammate's pace, while a 14.339 puts Lawson sixth.

In the Red Bull garage there is a lot of activity at the rear of Verstappen's car.

With 14 minutes remaining, Hamilton switches to hards, as do Bearman and Hadjar.

Hirakawa complains of bouncing in Turn 9, which was "not very nice".

All three compounds are in use as the race sims get underway.

Alonso calls for more straight-line power. He subsequently asks for the car to be checked as he feels something is wrong. He pits and climbs from his car.

At Alpine, Colapinto's session also appears to be at an end, his car up on its stand.

Russell might be down in 11th, but he and his teammate, like the Williams pair, have not run the softs. The Mercedes driver has also completed the most laps (31).

Verstappen is back on track.

The session ends. Norris is quickest, ahead of Verstappen, Hamilton, Leclerc, Piastri, Lawson, Bearman, Hadjar, Tsunoda and Gasly.

Russell is eleventh, ahead of Stroll, Alonso, Hulkenberg, Sainz, Bortoleto, Hirakawa, Antonelli, Martins and Colapinto.

Check out our Friday gallery from Barcelona here.