Ahead of today's final free practice session the air temperature is 24 degrees C, while the track temperature is 29 degrees. Baku being the City of Winds, it is understood that the city will live up to its name today with strong gusts expected to cause issues for the drivers today and even more so during tomorrow's race. To add to the fun there is a 20% chance of rain over the next hour.
Daniel Ricciardo topped the timesheets when it mattered yesterday, Red Bull looking very strong here on both the softer compounds. After crashing out in FP1, Max Verstappen looked more settled in FP2 until suffering a late sensor issue.
Both Mercedes drivers were over 0.7s off the pace, with Valtteri Bottas once again out-pacing his illustrious teammate.
While Ferrari had a poor opening session, Kimi Raikkonen was second in FP2, though Sebastian Vettel's poor showing - according to the man himself - was down to the man himself.
Fernando Alonso was best of the rest, heading a midfield that appears to see its order change with the wind... yesterday suggesting that Force India, Renault and Haas are looking strong.
That said, Force India, like Williams and Mercedes, looks set to benefit from new higher engine modes that can be run longer from this weekend.
Grip was a major issue yesterday, with almost everyone having an off or lock-up at one stage or another. Graining also looks likely to be an issue for some drivers.
Also worth noting that some driver may opt to qualify on the supersoft which is more durable than the ultra. However, with most teams having adopted a somewhat aggressive tyre strategy here, there is a question mark over whether they'll have enough of the red-banded tyres... this particularly applies to the big three.
Alonso leads a queue of cars out on to the track, Leclerc, Vandoorne, Magnussen and Ericsson follow. All are on ultras.
Hulkenberg, who says the track is "dirty", is advised that there are reports of spots of rains at Turns 17 and 18. The German is the only driver to sport supers on his car.
As Ricciardo posts the first time of the day (46.147) he's advised of a tailwind at the entry to T2 and exit to T4.
Verstappen posts 45.979, Raikkonen 45.075 and Vettel 44.758 as Bottas heads out. The Finn posts 50.129 before making a mistake at T1 and ruining his next lap.
Gasly complains that his steering is light in right corners and heavy in left corners.
PBs in all three sectors see Ricciardo split the Ferraris with a 44.861.
As Raikkonen looks set to improve, Hamilton is also on a hot lap.
The Finn posts 43.877 while Verstappen responds with a 44.563 and Hamilton 44.109. Moments later, Vettel bangs in a 43.642.
Behind the big six, Gasly is quickest, ahead of Hartley, the only drivers to have posted times thus far.
Hartley runs out of track and heads off down the escape road at T15. The Kiwi blaming a Ferrari that was in the way.
Vettel improves again, the German stopping the clock at 43.176 as the issues of yesterday seem a lifetime ago.
"I'm losing the rears towards the end of the lap," warns Stroll as he goes fifth with a 44.123.
Hamilton, who is about to pit, only wants to change his rears. Elsewhere, Magnussen is advised that his tyres are on the cold side.
Stroll heads down the escape road at T3.
"Looks like ultrasoft should be the optimal qualifying tyre," says Pirelli, "so everyone trying it out during this session. Track is evolving quite quickly, but it's still very slippery out there."
Twenty-five minutes in and we've still to see times from Hulkenberg, Ocon or Perez, who could be saving their tyres.
Following an off at T15, Grosjean asks his team what caused it. "Sorry guys, I'm really struggling here, what happened, was it rear-locking?" he asks.
Bottas goes off at T7 as Magnussen posts 44.655 to go seventh, just ahead of Alonso.
Back in the pits following his off, as mechanics swarm over the car and remove the engine cover it suggests his issue was about more than tyres.
Going quickest in the final sector, Perez improves to sixth with a 44.272.
Issues also for Raikkonen, who has been in his garage for some time, the problem thought to be exhaust-related.
"OK, I've got ******* loads of oversteer pretty much everywhere," moans Grosjean, though onboard footage appears to confirm his view.
As Ocon leapfrogs his teammate with a 44.220, Bottas has another moment.
Clearly motivated, Perez posts PBs in all three sectors, crossing the line at 43.936 to go third, behind the two Ferraris. Nonetheless, he remains 0.76s off Vettel's pace.
Down in 16th and 17th, the Renault duo remain the only drivers on the supersofts.
Raikkonen and the Mercedes duo head out on fresh ultras. Vettel's have done on lap.
PBs in all three sectors see Bottas go second (43.659), albeit 0.393s off Vettel's pace. Hamilton posts 43.874 to go third, the Briton enduring a somewhat scruffy lap.
Raikkonen posts a PB in S1, before going quickest in S2. At the line the Finn posts 43.493, second but still 0.317s adrift of his teammate.
Vettel responds with a 43.091, the German quickest again in S2.
Hamilton improves (43.553) but the Briton is still 0.462s off the pace. In the Mercedes garage, Toto Wolff looks far from happy.
Again Raikkonen posts a PB is S1, maintaining the pace in S2. Losing time in S3 he fails to improve.
"Where are we weak?" asks Hamilton. The Briton subsequently goes quickest in S1, but struggles in S2 and loses time. Despite another weak sector he improves to 43.452, still 0.36s off Vettel's pace.
Hulkenberg's session appears to be over. Currently 17th, he is in the garage with his crew stripping his car down.
Oh dear. The session is red flagged after the cameras pick up on Sirotkin who has clearly hit a wall. Replay shows the Russian carrying too much speed and running wide into the barrier at T3. "Sorry guys," he says. "I crashed it at Turn 3, sorry for that."
All of which will compromise the qualifying sims of his rivals, not least the Red Bull duo who had just headed out.
The session resumes with three minutes remaining, just about time for one flyer.
Vandoorne heads the queue of eager beavers keen to get back to work. However, he is quickly overtaken by Verstappen.
All are on track bar Sirotkin (obviously), Hulkenberg and Magnussen.
Vettel and Hamilton opt to pit.
Both Red Bull drivers post PBs in S1. Verstappen crosses the line at 43.519 to go fourth, while Ricciardo pits following a poor S2.
The session ends. Vettel is quickest, ahead of Hamilton, Raikkonen, Verstappen, Bottas, Perez, Magnussen, Stroll, Ocon and Sirotkin.
Alonso is eleventh, ahead of Ricciardo, Gasly, Leclerc, Grosjean, Sainz, Hulkenberg, Vandoorne, Ericsson and Hartley.
Compared to yesterday, it's night and day for Vettel, while Red Bull appears to have lost ground. An intriguing session that sets us up nicely for the remainder of the weekend.
Check out our Saturday gallery from Baku, here.