Ahead of today's qualifying session the air temperature is 26 degrees C, while the track temperature is 44 degrees. It is bright and sunny but also very windy.
Having set the pace in both of yesterday's sessions, this morning Lewis Hamilton could only manage third, while Valtteri Bottas, following two engine changes overnight, was fourth.
Whether the Italian team was sandbagging yesterday, or Mercedes this morning, remains to be seen. Certainly, in the battle of the updates yesterday sent a shiver down quite a few spines in the paddock and in the media room.
With this being the scene of winter testing, where Ferrari's improvement first became apparent, it is fitting that once again Barcelona might prove the form indicator.
Red Bull appears to have taken a step forward, but the initial signs are that it still isn't enough and that the Austrian team has much work still to do.
While the titanic battle for the title holds our attention, so too an equally fierce battle is raging behind for supremacy in the midfield. Over the course of the sessions thus far we have seen Haas, Renault and Williams - well Felipe Massa - all looking strong, with Toro Rosso also up there. Surprisingly, Force India hasn't been that impressive thus far.
On the other hand, full marks for effort and commitment to Fernando Alonso, who, following yesterday's nightmare, posted the tenth best time in FP3, teammate Stoffel Vandoorne's 19th place surely the better indicator of where McLaren stands at present.
Whatever want before, it is the next hour, particularly the final stages of Q2 and Q3 when we shall see the true pecking order, and whose upgrades have worked whose have some way still to go.
Following an issue late in this morning's session, Ferrari elected to change the engine in Vettel's car after discovering a water leak, which, apart from anything else, takes him that much closer to the penalty zone, this being his third engine of the season.
As we await the green light, Vettel sits quietly at the back of his garage, watching the crew work on his car.
Green light... but it is almost a minute before an engine fires up, it is that of Vandoorne. Vettel follows the Belgian down the pitlane, the German eager to get an installation lap under his belt.
It's the mark of the man that Vettel thanks his crew - in Italian - as he laps the circuit.
Sadly moments later, the German is told to "stop the car, stop the car now". Are you sure?" he asks. "Try to reach the box," he is told.
Meanwhile, Vandoorne has posted 23.219 to get things underway.
As Grosjean spins in T13, not only has Vettel not "boxed" he has gone quickest in S1. He maintains the pace in S2, finally crossing the line at 20.939 to go quickest... and moments earlier it seemed terminal.
As more drivers head out, Hamilton goes quickest in the first two sectors, crossing the line at 20.511. Bottas goes third with a 20.991.
A 22.390 sees Massa go fourth but he is instantly demoted when Sainz posts 22.082.
Despite a scrappy final sector, Ricciardo goes fourth with a 21.704, leapfrogged moments later by his Red Bull teammate who posts 21.430.
Raikkonen casually posts a series of PBs, crossing the line at 21.120 to take fourth.
Perez goes seventh (21.998) as Vettel and Bottas head out again even though both seem secure. Then again, in the German's case he is probably acquiring some data for the team.
Alonso goes 12th (22.345), and with 4:3 remaining the drop zone comprises Grosjean, Stroll, Palmer, Magnussen and Kvyat.
Raikkonen also goes out again, this time posting 20.742, just 0.231s off Hamilton's pace.
Grosjean improves to 7th with a 21.822 while teammate Magnussen goes 8th.
As the clock ticks down the bottom half of the timing screen is green as drivers post a series of PBs.
Alonso goes tenth while Hulkenberg can only mange 12th. Stroll fails to improve as do Stroll and Palmer.
A late improvement for Massa proves costly for Ericsson who misses the cut, just...
Quickest is Hamilton, ahead of Raikkonen, Vettel, Bottas, Verstappen, Ricciardo, Grosjean, Ocon, Sainz and Magnussen.
We lose Ericsson, Palmer, Stroll, Vandoorne and Kvyat.
Making the cut by the skin of his teeth, Massa admits he was struggling to make his tyres work.
The lights go green and the Mercedes duo are first out, followed by Raikkonen.
A mistake in T1 sees Bottas abandon his lap, while Hamilton trades fastest sectors with Raikkonen.
The Briton posts 20.210 while the Finn loses time in S3 and posts 20.621.
Raikkonen admits to making a mistake in the final chicane.
A 20.300 sees Bottas take second, the Finn just 0.090s off his teammate's pace.
Hulkenberg is the fifth driver to post a time, the German crossing the line at 21.759. Moment later he is bumped down when Sainz posts 21.385.
Ricciardo goes fourth but moments later is demoted by his teammate, the Red Bulls still 0.5s off the pace.
Vettel splits the Mercedes with a 20.295, just 0.085s off Hamilton's best.
As Grosjean goes tenth (21.517), it is a particularly scrappy lap with a couple of lock-ups. He is subsequently demoted by his teammate and Alonso.
With 5:00 remaining, the drop zone comprises Grosjean, Massa, Hulkenberg, Perez and Wehrlein.
The top six stay put, but from seventh (Sainz) downwards, everyone is on track.
Grosjean and Hulkenberg look set to improve, indeed the German goes eight. However, an off at the final chicane for the Frenchman ends his hopes.
A 21.151 sees Alonso go seventh, while Massa also appears to have made the cut.
As the crowd erupts, the big shock is that in those final few minutes another local here, Sainz, has slipped from seventh to twelfth.
Quickest was Hamilton, ahead of Vettel, Bottas, Raikkonen, Verstappen, Ricciardo, Ocon, Massa, Perez and Alonso.
We lose Magnussen, Sainz, Hulkenberg, Grosjean and Wehrlein.
A casual observer might think McLaren has taken pole such is the atmosphere in the garage where everyone is grinning from ear to ear.
Though the lights are green it is almost two minutes before there are any takers, the Mercedes duo leading the way followed by Vettel and ten Raikkonen.
In the first sector, Raikkonen has the edge, while countryman Bottas is quickest in S2. At the line Bottas posts 19.390 with Hamilton posting 19.149. Vettel crosses the line at 19.661 while Raikkonen posts 19.661.
No sooner has Ricciardo gone fifth (20.265) than he is demoted by his teammate who posts 19.767.
The top three covered by 0.290s, Ocon, Massa, Perez and Alonso are clearly only going for one late run.
With 3:20 on the clock, Alonso gets the final assault underway, much to the delight of the crowd.
As he prepares for his final flyer, Bottas is stuck behind former teammate Massa.
No improvements for either Mercedes driver in S1, while Vettel goes quickest in the opening sector. Moments later Raikkonen goes even quicker.
Vettel is quickest in S2 and when Hamilton and Bottas fail to improve all eyes turn to the Ferraris. Vettel crosses the line at 19.200 to take second while Raikkonen can only manage 19.439 which puts him fourth. We say 'only', when in fact the top four are covered by just 0.290s.
Verstappen remains ahead of his Red Bull teammate while a 21.048 sees Alonso take an amazing seventh, which puts him ahead of Perez, Massa and Ocon.
So, Hamilton takes pole ahead of Vettel, Bottas, Raikkonen, Verstappen, Ricciardo, Alonso, Perez, Massa and Ocon.
Magnussen will start eleventh, ahead of Sainz, Hulkenberg, Grosjean, Wehrlein, Ericsson, Palmer, Stroll, Vandoorne and Kvyat.
In a change to the format, the top three drivers head out on to the track to be interviewed.
"I really appreciate all the support," says Hamilton. "I'm super proud of the team that we could get back up there.
"The last lap was so-so but I could hear the guys cheering," he adds, looking up to the stands. "It's always a morale boost, these guys make the weekend what it is."
"I've been coming here a long time, so many laps, and still the chicane is tricky," laugh Vettel, referring to the late error that cost him pole. "A big thank you to the team, we had to change the engine last minute... Kimi's team helped out. They did an engine change sub two-hours, unbelievable, it's a miracle they got me out!"
Similarly, Bottas pays tribute to his crew. "The guys did an amazing job to change my engine," he says. "Not ideal, but it is what it is."
Finally, Alonso is brought out for the fans to applaud, nothing less than the Spaniard deserves.
With 0.051s separating Hamilton and Vettel, and the German making a mistake in the final sector, despite all the updates we appear to still have a well matched title fight.