Ahead of today's free practice session, the air temperature is 20 degrees C, while the track temperature is 20 degrees.
Best way to sum up things before the session gets underway is to tell you what Bob Constanduros told us just moments ago.
"It's dripping with rain, no sign of Mount Fuji, temperature still high at 20 degrees for both track and ambient. Just did interview with Lewis who says that there is quite a lot of grip here even in the wet, but the race is expected to be dry.
"Qualifying will probably be wet, times only eight seconds more or so. Difficult decision whether to go for wet set-up in qualifying for dry set-up for the race; no changing after qualifying of course, and a big compromise anyway here with a 1.4 kms straight, and altitude of 565m. Hmmm."
As the lights go green, and Rosberg heads down the pitlane, the rain has stopped, however, the session has been declared wet. As Bourdais, Kubica, Hamilton, Button, Coulthard, Alonso and the rest, follow Rosberg, Race Control advises that no further rain is expected in the next thirty minutes. Nonetheless, the track is already very, very wet.
Everyone bar the Ferraris and Barrichello has been out for an exploratory lap and then returned to the pits. However, five minutes into the session the Honda driver heads down the pitlane, joined by his teammate, who has already been out.
The Englishman posts the first time of the day, crossing the line at 1:28.661.
Glock, Kubica and the Force Indias are on track, and it isn't long before the Toyota driver raises the benchmark with a 28.186. Raikkonen is also on track.
As one would expect, Vettel goes quickest, with Bourdais going second, but soon Kovalainen is at the top of the timesheets, with Raikkonen only managing fifth.
With Massa still to make an appearance, and seventeen minutes of the session gone, Hamilton goes quickest with a 27.410. Vettel goes second and Glock fourth.
As Massa heads down the pitlane, Hamilton raises the benchmark with a 26.453. Elsewhere, Bourdais takes an excursion into the Japanese countryside.
It is spitting with rain on the far side of the track, however, after a minute or two it stops again.
A 26.289 sees Glock go quickest, as Rosberg and Nakajima, both on inters, go third and fourth and Massa seventh. Replay shows Rosberg going straight on at the end of the main straight, however, thankfully there's a very big run-off.
Hamilton re-takers the top spot (25.901) as Massa, another on intermediates, goes third (26.503).
As the times improve, Coulthard is told that now is the time to switch to inters, the Scot agrees.
Massa goes quickest in the second sector, and second overall, albeit 0.271s down on his title rival.
Next time around he goes quickest in the first sector, but then loses over a second in the second sector behind his Ferrari teammate, who eventually pulls to one side a allows him through. However, the Brazilian's lap is ruined.
As Bourdais goes second, having gone quickest in the first sector, Race Control advises that there will be no further rain during the session. Piquet goes fifth, ahead of the Williams.
A 25.709 sees Massa go quickest, almost forty minutes into the session. Elsewhere, Piquet improves to fourth, ahead of Vettel, Glock and Kovalainen. Raikkonen is down in fifteenth, sandwiched by Heidfeld and Button.
Glock goes second (25.857) and immediately goes quickest in the first sector of his next lap, there's no stopping the 2007 GP2 champ this weekend.
From out of nowhere, as ever, Webber produces a 25.974 to go fourth. Teammate Coulthard is seventh.
With just over fifteen minutes remaining, Raikkonen, the BMW duo and Alonso are at the wrong end of the timesheets. However, as Bob Constanduros advised earlier the drivers face a tough decision, with rain expected for qualifying but a dry race, which way do they go when it comes to set-up, wet or dry?
Nakajima, having posted a personal best in sector two, improves to sixth overall. Elsewhere, Raikkonen 'improves' to fifteenth. Next time around the Finn posts 26.498 to go thirteenth.
Replay shows Raikkonen having a 360, before heading back to the pits for a practice pitstop, complete with lollipop man.
With just over six minutes remaining, the final assault is about to begin, and it looks as though conditions are improving, certainly in some parts of the track.