Ahead of today's opening session, the air temperature is 17 degrees C, whilst the track temperature is 20 degrees.

In the hours leading up to this session there's been heavy rain, there's been hail and organisers are warning that strong winds and rain are forecast for the rest of the day. "Please stay indoors or under cover", they helpfully advise.

In fact, about an hour before the start of the session the rain stopped and the strong winds began to dry the track... and then the rain returned.

As you'll be aware, drivers have three compounds to choose from, medium, soft and supersoft, though it's unlikely we'll see any of these over the next ninety minutes, most likely the full wets and inters. Whilst the rain stopped shortly before the start of the session, it has been declared officially wet with a 70% chance of further rain.

The lights go green, and Sebastian Vettel gets the 2016 season underway. He is followed by his Ferrari teammate Raikkonen and, shortly after, Verstappen. The Ferraris are on full wets whilst Verstappen is on inters. Hulkenberg, Rosberg, Bottas and Kvyat also on track, all on inters.

Whilst most head back to the comfort of the pits, Rosberg stays out, almost tripping up over Magnussen. Some parts of the Albert Park circuit significantly wetter than others.

Vettel might have been first out but it is countryman Rosberg who posts the first time of the year, the Mercedes crossing the line at 1:44.037.

A problem for Perez who has stopped at the end of the pitlane and has to be rescued by his pit crew.

Ten minutes in and Hamilton is one of the last to head out, leaving Gutierrez, Sainz and Haryanto as the only no-shows. The Briton, on inters, goes on to post 40.812.

Local hero Ricciardo looks likely to be the third driver to post a time however, having gone quickest in the opening two sectors he dives into the pits.

His place is taken by teammate Kvyat, who is joined by Rosberg and Raikkonen.

The sun is shining on the far side of the track.

A 40.754 sees Raikkonen eclipse the two Ferraris, as teammate Vettel heads down the pitlane. Both now on inters.

Despite going quickest in S1, Vettel abandons the lap and heads to the pits. The track falls silent.

After a short break, Ricciardo and Sainz fire up and head down the pitlane, the Australian is on the medium rubber. A problem for Sainz who grinds to a halt as he enters the pitlane.

Both McLarens on track, both on the soft rubber, Hamilton is back on track, also on the yellow-banded tyre as are Hulkenberg, Bottas and Massa.

Ricciardo goes quickest (32.394), with teammate Kvyat going second (34.123) moments later. Alonso posts 36.957 to go third - on softs - at which point it starts raining again.

Palmer (inters) does well not to clout a wobbly Haryanto as worsening conditions and being on the slicks almost take their toll.

Whilst some parts of the track look fine, it is still quite wet between turns 4 and 9.

As the drivers head back to the pits, after forty minutes of running, it's: Ricciardo, Kvyat, Alonso, Raikkonen, Hamilton, Rosberg, Palmer and Magnussen.

As conditions improve, Button is back on track, as is Verstappen, both on inters.

Button posts 43.508 to go seventh, whilst Verstappen goes fourth with a 40.249. Shortly after the Dutch youngster does well not to lose it as he gets perilously close to the wet Astroturf at T11.

Improving to 43.217, Button heads back to the pits as teammate Alonso takes his place on track. The Spaniard having sole use of the Albert Park track.

As Alonso seeks to improve, he is joined by the Haas duo, Gutierrez having only completed one lap thus far. The Mexican complains of inconsistencies in power delivery.

Nonetheless, the Mexican posts his - his team's - first time, a 45.771, which puts him ninth on the sheets. Having improves to seventh (41.780), Gutierrez is joined on the timesheets by teammate Grosjean who posts 43.443.

The sun is now shining, but as Grosjean heads back to the pits there is no mad rush to return to work from his rivals.

Finally, Verstappen (softs) breaks the silence. Elsewhere, teammate Sainz' technical woes appear to have carried over from last year, the Spaniard has completed just one lap.

It was going so well, having looked set to improve, Verstappen spin after pushing just a little too hard in T6/7. In all honesty, the track might still be a little bit wet there.

Meanwhile, Hulkenberg has banged in a 31.681 to go quickest, with teammate Perez posting 33.370 to go third. A 34.796 sees Nasr go sixth.

With conditions the best we've seen them, more and more drivers pour on to the track.