Ahead of today's opening practice session the air temperature is 29 degrees C, as is the track temperature.

A couple of hours ago the circuit was hit by a massive thunderstorm. It stopped raining a while ago but despite the heat there are many parts of the track that remain damp, consequently the session has been declared 'wet'. Interestingly, the track is also littlered with leaves.

With McLaren having won the last three races, all eyes are on the Woking team this weekend, and not only to see if its winning streak continues. However, on a track more suited to the Red Bull, perhaps Sebastian Vettel and Mark Webber can get back into the title fight.

Meanwhile, at Ferrari, Felipe Massa can help keep his seat for 2013 as he sports teammate Fernando Alonso's title bid, while Mercedes is relying on its various upgrades.

Romain Grosjean is back in the Lotus after his one-race ban, while the only reserve driver on duty is Ma Qing Hua is back in the HRY of Narain Karthikeyan.

Tyre compounds are soft (prime) and super-soft (option).

The lights go green and Perez leads the way, followed by Vergne, Ricciardo and Pic. All are on inters. A number of drivers are sporting new helmet liveries, Vettel's actually features small flashing silver lights. Ye gods!

HRT is running a number of updates including a new floor, therefore it comes as no surprise that it is coated in flo-vis paint.

Five minutes into the session all but Grosjean and Hamilton have been out for an installation lap. Most on inters but a few on full wets.

A rapid Schumacher almost runs into the back of a slow Rosberg, the rain lights on both Mercedes flashing but clearly not enough.

Nine minutes into the session, Hamilton is the last man out, the Englishman lucky not to cloud one of the numerous photographers gathering not only for a shot of the man in the news but also the raft of updates on the car.

Perez comes out for a second run but subsequently returns to the pits. While the teams feel there s no point running on a drying track the fact is that rain is expected for must of the weekend.

Out for a second run, Glock posts a 2:24.476 before returning to the pits.

Kobayashi leaves the pits, followed by Vettel, the overhead shots revealing that due to the humidity the damp patches remain damp.

Despite setting a strong pace in the first two sectors Vettel dives back into the pits. However, Vergne completes his lap and goes quickest with a 2:04.866.

Grosjean goes second with a 2:05.130, the Frenchman claiming that his Monza ban has taught him a lesson. We shall see Romain, we shall see.

Hulkenberg posts 2:02.852 still way off the pace set in FP1 last year when Hamilton led the way with a 1:48.599.

Just one lap later, Hulkenberg complains that his inters are already "going off".

Alonso goes quickest with a 2:01.573, ahead of Hulkenberg, Ricciardo, Grosjean, Vergne, Kobayashi, de la Rosa and Glock.

Kobayashi is the first driver to switch to dry rubber (soft), the Sauber driver immediately going quickest (1:58.550). The news is passed on to Raikkonen who aborts his lap and returns to the pits.

As Rosberg (primes) goes second, Kobayashi raises the bar with a 55.651.

Senna pushing hard, riding the kerbs and getting up close and personal with the walls as he improves from seventh to third with a 59.447.

Moments later, Schumacher posts 56.834 to leapfrog the Williams driver. Elsewhere a big lock up at the chicane for his Mercedes teammate.

"No rain in next 30 minutes but risk of thundery shower before end of FP1," warn the timing screens.

As Alonso perseveres with the inters, remaining sixth, Button posts 2:01.890 to seventh on softs.