This weekend's Malaysian Grand Prix - the second round on the 2009 Formula 1 World Championship calendar - could be disrupted by thunderstorms, throwing an added element of the unknown into an already highly unpredictable season.

The race - held annually since 1999 around the Hermann Tilke-designed Sepang International Circuit (SIC) - is invariably the hottest and most draining on the sport's schedule, but that could change this year, with temperatures forecast to dip as low as 24?C on Sunday.

Combined with a later start time than usual - 5pm rather than 3pm, as was the case in Melbourne last weekend, in a bid to make the 56-lap event more attractive to European television viewing audiences - that means the possibility of darkness descending before the chequered flag has fallen is now very real, with the Malaysian Meteorological Department predicting the thunderstorms will hang around right the way through the weekend.

"The situation for teams working in the wet is trickier," acknowledged SIC chief executive officer Razlan Razali, speaking to local newspaper the Malaysia Star. "What was the hottest race in the world could now turn to a twilight event because if it gets dark, it gets even more challenging for the teams and drivers.

"I hope for a safe race, but on Monday it rained heavily during the predicted race duration. If it rains, hopefully it happens before the race, as fans can watch the race on a wet track and then enjoy the post-race Jamiroquai concert."