Ahead of today's second practice session, the air temperature is 19.7 degrees C, while the track temperature is 23.2 degrees. It is overcast, but at least its dry, at least for now, Race Control revealing that there is a 30% chance of rain.
Alex Albon posted the fastest time in FP1, a session in which much of the running was compromised by the conditions, then promptly crashed out just moments after switching to slicks.
During the break, as a result of his crash, Albon has had a new floor fitted and the front of the car rebuilt. Ahead of the green light work continues on his car, and it is unlikely he'll be out on track anytime soon.
With conditions expected to be dry and warm tomorrow and on Sunday, clearly some teams felt it was not worth taking unnecessary risks, consequently Lewis Hamilton and Max Verstappen were among the four drivers that didn't post a time.
Having handed his car over to Nicholas Latifi in FP1, Robert Kubica will be keen to get to work this afternoon.
The lights go green and Giovinazzi leads the way, followed by Norris, Raikkonen and Grosjean. Bottas is among the early risers.
As more drivers head out there's a mixture of hards and mediums.
Of the first wave, Bottas goes quickest (natch), with a 10.812, ahead of Giovinazzi, Ricciardo and Grosjean.
Sadly, no sooner has he headed out than Kubica is off on the entry to Turn 3, which brings out the red flag.
The Pole appeared to have oversteer in the corner and went off onto the wet grass, at which point he was a passenger as the Williams nose-dived into the barriers, damaging the left-hand side of the car.
Moments before Kubica's off, Magnussen had run over the inside kerb at Turn 3, the spray thrown up by the Haas confirming that the kerb was wet and slippery.
The session resumes, and soon there are ten, eleven, twelve driver out there, among them Hamilton and the Red Bull pair.
Verstappen rockets to the top of the timesheets with a 10.051, eclipsing Bottas' best by 0.761, albeit on the medium rubber while the Finn was on hards.
Albon goes second ((10.750) on the mediums, as Hamilton, Vettel and Leclerc begin their first flying laps.
Hamilton posts 9.938, despite only being quickest in S2, while Leclerc goes third (10.297).
"Downshift is very aggressive," reports Hamilton, who is on mediums, unlike his teammate, "very poor."
A 10.157 sees Vettel go third, as Gasly has a vicious snap in Turn 2.
Leclerc improves to 9.820 to go quickest, but is demoted when teammate Vettel posts 9.570.
"I am pushing, I am pushing," shouts Grosjean when advised that Kvyat is coming up behind.
"It's starting to spit a little bit," advises Hamilton.
Like Hamilton, Hulkenberg reports a problem with his downshifts.
"My steering wheel is turning to the right," warns Kvyat, "when I'm in a straight line."
Hulkenberg is told that while he may see spots of rain on his visor, it is nothing to worry about. That's easy for the engineer to say.
Problems at Red Bull where the crew appear unable to fit a new front wing on Verstappen's car.
Behind the big six, or big three, depending on how you look at it, Gasly is best of the rest, ahead of Sainz, Giovinazzi and Kvyat.
When Hamilton asks where he is down, he is told "it's mainly straight-line speed to Vettel".
As Ricciardo is told that the rain is getting heavier, there is heavy duty work going on at the rear of Norris' McLaren.
"This rain doesn't show up on the radar," Stroll is helpfully advised, as Verstappen reports that it is "quite slippery, mate".
Thirty-six minutes in, Russell is the first driver to head out on softs. Failing to improve his time, he reports: "Tyres weren't ready".
Meanwhile, more and more drivers switch to the red-banded rubber.
Grosjean runs wide I the infamous Turn 13, which means he fails to improve his time.
No such issues for that wily old fox Raikkonen, who goes fifth with a 10.210. Teammate Giovinazzi goes eighth (10.419).
As Magnussen goes eighth (10.383), Vettel is setting a blistering pace. Meanwhile, the Mercedes pair almost trip one another up, with Bottas subsequently getting in the way of Vettel.
"Valtteri's just sitting there," complains Hamilton, who, like Vettel, had to abort his lap
A spin in Turn 1 for Kvyat.
Leclerc goes quickest with a 9.238, with Bottas posting 9.373 moments later.
Vettel raises the bar with a 9.217.
More problems for Hamilton who encounters a slow Toro Rosso (Gasly) in Turn 1, the Englishman having to run wide in order to avoid it. The Frenchman subsequently causes Grosjean to take avoiding action also.
Hamilton can only manage 9.440, which is only good enough for fifth.
"Is anyone improving," asks Sainz, the Spaniard clearly disappointed to that several drivers are.
Content with his qualifying sim, Vettel switched to his high-fuel, long run programme. "We'll focus on the long runs," he says, "I know what I can do on these tyres, so don't worry."
Vettel is quickest, ahead of Leclerc, Verstappen, Bottas, Hamilton, Magnussen, Ricciardo, Raikkonen, Albon and Sainz.
"If you can brake later for Turn 1, that would be good," Stroll is told.
More and more drivers follow Vettel's example and switch their focus to long runs.
After reporting a loss of power, Giovinazzi is out of his car as his crew get to work.
Replay shows Leclerc being released into the path of Bottas.
Everyone is on softs bar Leclerc, who is on mediums.
Russell reports understeer in Turn 13.
"Engine problem, engine problem," reports Gasly as he slows down and parks on the back straight, smoke rising from the rear of the Toro Rosso.
The VSC is deployed.
As the car is pushed to safety, the VSC is withdrawn.
Vettel and Verstappen appear to think it's Sunday, as the Dutchman hunts down the Ferrari.
"Good laps, good laps, how are the tyres," Magnussen is asked. "Still good," he replies.
Check out our Friday gallery from Interlagos, here.