Jenson Button beat the showers that dogged second practice ahead of Sunday's Monaco Grand Prix to record the fastest time of the day.
With rain forecast as the session began, it forced all drivers to hit the principality street circuit to get in dry running before the dangers increased on a potentially greasy track.
After just 25 minutes, with the gloom closing in, the first light shower did enough to send the cars scurrying back into the pits.
At that stage McLaren star Button held sway with a lap of one minute 15.746secs, a time that was never to be bettered as the rain drifted in and out, resulting in interspersed periods of activity and quiet.
At least there was the opportunity for the teams to try out the intermediate Pirelli tyres, designed for such damp conditions.
Depending on which website you believe, there is the prospect of further rain over the weekend, but then the weather in such a microclimate as this part of the world is as unpredictable as the racing we have so far seen.
Button is one of five different drivers to have won a race this year, with history beckoning on Sunday as a season has never started with six different winners of the first six races.
In truth, no team will have gathered too much useful data today to prepare them for the race, despite spending three hours out on track.
The rain played its part, but given there is no running on Friday in Monaco - a long-held tradition - the nature of the roads used for the race could alter considerably by qualifying on Saturday.
As in the first session, Lotus' Romain Grosjean was forced to settle for second best, initially to Ferrari's Fernando Alonso, and then Button, with the Frenchman 0.392secs adrift.
The Ferraris of Felipe Massa and Fernando Alonso finished third and fourth, the Brazilian for once this season ahead of his team-mate on the timesheet and under pressure this weekend to improve on his poor performances to date.
Race winner in Spain last time out, Williams' Pastor Maldonado, was fifth quickest a second down, followed by Nico Rosberg in his Mercedes.
Red Bull duo Mark Webber and reigning champion Sebastian Vettel were in seventh and 10th, the latter 1.5secs down, with Sauber's Kamui Kobayashi and Michael Schumacher in his Mercedes sandwiched between the pair.
Lewis Hamilton trailed in 11th, 1.6secs off his team-mate, with Force India's Paul di Resta narrowly behind his fellow Briton in 12th.
Heikki Kovalainen had earlier brought a premature halt to first practice when the Renault engine in his Caterham blew nine minutes from the end of the session.
As the Finn was blasting through the tunnel at the time, white clouds of smoke billowed into the air, making visibility almost zero, forcing the stewards to red flag and eventually bring an early end to proceedings.
Back on track in FP2, Kovalainen finished down in 21st, 4.2secs behind Button.
Times
1 Jenson Button (Gbr) McLaren-Mercedes 1min 15.746secs
2 Romain Grosjean (Swi) Lotus-Renault 1:16.138
3 Felipe Massa (Bra) Ferrari 1:16.602
4 Fernando Alonso (Spa) Ferrari 1:16.661
5 Pastor Maldonado (Ven) Williams-Renault 1:16.820
6 Nico Rosberg (Ger) Mercedes GP 1:17.021
7 Mark Webber (Aus) Red Bull-Renault 1:17.148
8 Kamui Kobayashi (Jpn) Sauber 1:17.153
9 Michael Schumacher (Ger) Mercedes GP 1:17.293
10 Sebastian Vettel (Ger) Red Bull-Renault 1:17.303
11 Lewis Hamilton (Gbr) McLaren-Mercedes 1:17.375
12 Paul Di Resta (Gbr) Force India-Mercedes 1:17.395
13 Bruno Senna (Bra) Williams-Renault 1:17.655
14 Nico Hulkenberg (Ger) Force India-Mercedes 1:17.800
15 Sergio Perez (Mex) Sauber 1:18.251
16 Vitaly Petrov (Rus) Caterham-Renault 1:18.440
17 Jean-Eric Vergne (Fra) Toro Rosso-Ferrari 1:18.522
18 Daniel Ricciardo (Aus) Toro Rosso-Ferrari 1:18.808
19 Kimi Raikkonen (Fin) Lotus-Renault 1:19.267
20 Timo Glock (Ger) Marussia-Cosworth 1:19.309
21 Heikki Kovalainen (Fin) Caterham-Renault 1:20.029
22 Charles Pic (Fra) Marussia-Cosworth 1:20.240
23 Pedro de la Rosa (Spa) HRT-Cosworth 1:20.631
24 Narain Karthikeyan (Ind) HRT-Cosworth 1:20.886
