Ahead of today's sole free practice session, the air temperature is 16.6 degrees C, while the track temperature is 28 degrees.
Mercedes topped the timesheets in both of yesterday's sessions, Valtteri Bottas in the morning and Lewis Hamilton in the afternoon. It was subsequently revealed however that both cars had incurred damage and therefore there is likely to be more pace there.
Max Verstappen was second quickest in both sessions, however the Dutchman wasn't entirely happy with his car's handling.
Indeed most drivers were unhappy with grip levels and there are already suggestions that Pirelli - not for the first time - has been conservative in its choice of compounds.
While Ferrari appears to have the edge in terms of the 'best of the rest', and Alpine appears to have taken a step forward, it is difficult to get an idea of McLaren's true pace here.
Much like McLaren, AlphaTauri has looked a little off the pace thus far this weekend, though the difficult conditions, in terms of the lack of grip and blustery winds, hardly help matters.
The hards are currently around 0.8 seconds per lap slower than the mediums, while the soft tyre is about 0.4 seconds per lap faster than the medium. The gap between the medium and hard is slightly less than expected, whereas the gap from soft to medium is as anticipated.
Michael Masi continues to tinker with the track limits rules, the FIA's race director deeming overnight that Turn 14 should join Turns 1, 4 and 15 as no-nos.
Over the course of yesterday's two session, no less than 65 times were deleted.
The lights go green but it is a couple of minutes before a driver heads out, and that driver is Stroll, his Aston Martin having been liberally daubed with flo-vis.
He is subsequently joined by Vettel, Schumacher and Mazepin.
There's an early spin for Schumacher at T14, while Mazepin also has a moment.
While the Aston Martin pair both pit following an install lap, Schumacher posts the first time of the day, a 23.026. Mazepin responds with a 24.955. The German is on mediums, while his teammate is on softs.
Mazepin improves to 22.430 and Schumacher to 22.777, as Tsunoda and Raikkonen head out.
"Anything we can help you with?" Schumacher is asked. "Not really," he replies, "I'm just trying to find the limit."
Mazepin and Raikkonen have their times deleted for running wide at different corners.
Tsunoda (mediums) goes quickest with a 20.997, while a 25.723 sees Alonso go fourth.
Raikkonen (softs) goes top with a 20.600, only to be demoted when another world champion, Alonso, posts 20.382.
Perez goes second with a 20.445, but is demoted when Tsunoda posts 20.161.
Ricciardo goes fourth with a 20.528 as Gasly has his time deleted.
A number of drivers are opting for two warm-up laps, and this appears to be Ricciardo's strategy.
Sainz goes fourth (20.405) on softs as Raikkonen remains quickest with a 19.944.
Norris is also opting for two warm-up laps, as Ocon goes quickest (19.672) on the mediums. The Frenchman is quickest in the first and final sectors.
Leclerc goes second (19.743) on softs, as the Mercedes pair head out, leaving Verstappen as the only no-show.
A 20.101 sees Sainz go sixth on softs, as Tsunoda improves to fifth (19.952).
With 36 minutes remaining, Verstappen finally heads out.
Norris goes tenth (20.165) and Ricciardo third (19.929), both on the softs.
Quickest in the first two sectors, Leclerc remains second, 0.002s off Ocon's pace.
The Mercedes pair are also going for two warm-up laps, Bottas' first is a 1:24 while Hamilton does a 1:28.
The VSC is deployed, but it is not clear why. Ah, an advertising hoard has been blown over.
That VSC wrecked a number of flying laps, not least those of the Mercedes pair, Verstappen and Vettel.
Stroll is currently the only driver yet to post a time.
Gasly goes quickest but his time is subsequently deleted, as is Hamilton's.
Perez goes quickest (18.840), while Verstappen goes third (19.141) and Bottas fourth (19.195).
An 18.755 sees Hamilton go top while replay reveals a 360 spin for Raikkonen at Turn 8.
Featuring a number of updates which his teammate doesn't have, Stroll can only manage a 20.716, while Vettel is currently on 20.214.
"I don't get why Lewis backs up so much," wonders Verstappen. "He has so much space."
Hamilton responds with an 18.735.
"I'll do a cool down after this," says Stroll. "No, no, no," comes the response, "your tyres aren't warm enough yet."
The Canadian subsequently posts a 20.090 to go 13th.
As attention turns to the qualifying sims, Hamilton heads out on fresh softs, as does Verstappen.
The Dutchman posts an 18.545, the only purple being the final sector.
PBs in all three sectors see Ocon consolidate fifth (19.146), teammate Alonso is currently 11th on 19.949.
"There are a couple of areas we're better," Christian Horner tells Sky Sports, "Turn 3 they are better.
"Last year this was a big Mercedes circuit, but hopefully we can take this form into qualifying and put them under pressure. Based on this, it's going to be really, really tight."
Raikkonen improves from 11th to 7th with a 19.415, and while Alonso goes third with an 18.735, the Spaniard subsequently has his time deleted.
Schumacher improves to 17th with a 20.271.
Hamilton heads out on fresh rubber, the Briton, again, opting for a double warm-up.
A spin in Turn 14 for Norris briefly brings out the yellows as Alonso has another time deleted.
The yellows causing Hamilton to abort his lap. Next time around he improves to 18.725, just 0.180s off Verstappen's best.
Perez goes fourth with an 18.840, the Mexican only improving in the middle sector.
Behind the Bulls and Black Arrows, Ocon is fifth, ahead of Leclerc, Norris, Gasly, Raikkonen and Sainz.
"It's that last sector all the time," says Verstappen, "I lose everything in that last sector. Loads of oversteer."
Meanwhile, Bottas is unable to improve on third.
Despite not posting a single PB, Verstappen consolidates his top spot with an 18.489, thereby extending the gap to Hamilton to 0.236s.
Vettel, currently 17th, complains of "big vibrations" on his current set of tyres. To add to his woes he has his time deleted.
It wouldn't be a proper session without Mazepin hitting the kitty litter, and the Russian duly obliges. The Haas driver going off at Turn 11.
A late improvement from Stroll, however he is still only 15th.
The session ends. Verstappen is quickest, ahead of Hamilton, Bottas, Perez, Ocon, Leclerc, Sainz, Norris, Gasly and Raikkonen.
Tsunoda is eleventh, ahead of Ricciardo, Giovinazzi, Alonso, Schumacher, Stroll, Russell, Vettel, Latifi and Mazepin.
Check out our Saturday gallery from Portimao, here.