Ahead of today's sole free practice session the air temperature is 20 degrees C while the track temperature is 22 degrees. Humidity is 87% which is higher than in Singapore!

Following heavy storms during the night it was fairly clear this morning only to start pouring down as the F3 cars took to the track earlier. Lots of spray, lots of spins, and lots of smiles in the McLaren garage, the Woking team sure to be able to turn things to its advantage.

Red Bull dominated both sessions yesterday, but today's conditions, which are expected to continue into qualifying will turn all that on its head. No doubt, in a quiet corner of the paddock, Bernie Ecclestone's been doing a rain dance.

As we await the start of the session - which has officially been declared wet - the rain has eased off, but there will be more to follow, much more. In the paddock Bernie Ecclestone chats with Helmut Marko and Niki Lauda - who looks ludicrous in a see-through plastic poncho.

The lights go green and Kovalainen leads the way, followed by di Grassi, Alguersuari, Glock, Buemi and Klien, all on intermediates. As Heidfeld heads into Turn 4 he is told that the weather will remain as is for the next thirty minutes.

Five minutes into the session, everyone has been out, McLaren running its two drivers with different set-ups, Hamilton using a higher downforce package than his teammate.

In the Mercedes garage Rosberg appears to be having the same problem untangling the leads on his headphones as we encounter with out iPhone headphones. So it's not just us.

Glock is the first driver to come out for a second run, followed by Heidfeld. The Virgin driver crosses the line at 1:25.972, which is 14.004s off yesterday's pace. Next time around the German posts a 24.642.

Heidfeld is the second driver to post a time (31.642), subsequently improving with a 23.897.

In the Ferrari garage, Giancarlo Fisichella - a previous winner here, and in the wet - looks awkward.

As more and more drivers take to the track, Barrichello goes quickest with a 22.612. However, moments later Buemi ups the ante with a 22.537.

Massa is the first of the big guns to come out for a second run, followed, shortly after, by Hamilton, Button and Webber. Despite the rain having increased in intensity, they are all on inters.

Hulkenberg goes quickest (21.277) ahead of Petrov as Massa - on his first flying lap - goes seventh with a 23.214.

Button goes fifth (22.277) and Hamilton sixth while Webber and Vettel go tenth and eleventh. Elsewhere, Alonso heads down the pitlane.

Button improves with a 21.564 but is soon eclipsed by his teammate who posts a 21.482. However, a 21.366 sees Webber go second, albeit 0.831s off Hulkenberg's pace.

The 'rain master' Schumacher goes sixth with a 21.981 as the rain begins to fall that little bit harder.

Alonso goes quickest with a 20.200 as Webber also improves but remains second.

After twenty-five minutes all but Klien and Kubica have posted times.

No sooner has Hamilton gone quickest with a 19.912 than former teammate Alonso posts 19.791, Vettel still almost 2s off the pace down in tenth. Kubica's first flying lap sees the Pole go ninth (21.049).

On the half-hour, the rain begins to ease off, Massa goes quickest with a 19.735 while Vettel posts 20.111 to go fourth.

Despite the rain easing right off conditions remain treacherous, as demonstrated by Sutil at Juncao, the German getting horribly out of shape.

Buemi goes quickest in the first sector, subsequently posting a personal best in S2. At the line it's 20.009 moving the Swiss up to fifth.

Button, still running the lighter downforce set-up, is down in seventeenth 1.540s off the pace.

Having gone quickest in the final two sectors Vettel goes quickest, the German crossing the timing beam at 19.500.