The heat, humidity and intensity of the Marina Bay Circuit makes the Formula One Singapore Grand Prix one of the most demanding for drivers and their teams, and looking at the weather forecast for this weekend’s race it appears there’ll be no respite from the extreme conditions.

The peak temperature will hit 90 degrees F (32 degrees C) on Sunday, and even though the race is run at night cockpit temperatures regularly exceed 120 degrees F (49 degrees C) and there are few straights along which to cool down.

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Changeable weather means yesterday’s prediction of thunderstorms are already obsolete. The latest forecast calls for mostly sunny conditions for the entire weekend. The actual race, though, starts roughly two hours after the sun goes down, at 8 p.m. local time.

The asphalt around the Marina Bay circuit is slippery, so Pirelli is taking its two softest tire compounds: soft and supersoft. This combination was last used at the Austrian Grand Prix and provides rapid warm-up and good mechanical grip to handle all 23 of the circuit's corners, the highest of any venue on the current calendar.

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So far during practice, Mercedes AMG duo Lewis Hamilton and Nico Rosberg have been the quickest, with Rosberg managing to edge out his teammate. Behind them, Infiniti Red Bull Racing’s Daniel Ricciardo and Ferrari’s Sebastian Vettel are showing some serious pace, with Ricciardo in particular setting times just a tenth off the pace of Hamilton and less than four tenths off Rosberg.

Going into tomorrow’s qualifying session and Sunday’s race, Hamilton leads the 2015 Drivers’ Championship with 252 points. Rosberg is second with 199 and Vettel is third with 178. In the Constructors’ Championship, Mercedes leads with 451 points versus the 270 of Ferrari and 188 of Williams.

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