Suzuka - Japanese Grand Prix organisers will decide at noon Friday (05:00 SA time) if the race weekend timetable, including Saturday qualifying, can go ahead as Super Typhoon Hagibis threatens the Suzuka circuit.
A spokesperson for the governing body FIA told AFP on Thursday that any decision to change the weekend programme rested with the local authorities in consultation with the FIA and Formula One.
The typhoon has already claimed casualties at the Rugby World Cup in Japan, with Saturday's England-France clash in Yokohama and the New Zealand-Italy match in Toyota City cancelled.
Two minor support races scheduled for Saturday at Suzuka have already been scrapped as a precaution.
Saturday's third free practice session and qualifying are likely to follow suit, but the volatile nature of Hagibis means even Sunday's race could be under threat, though the current forecast is for better weather that day.
Earlier, the FIA issued a statement saying the safety of fans and drivers would be the top priority as Hagibis - classed as "violent" and the equivalent of a Category Five hurricane - is predicted to make landfall near Tokyo on Saturday.
The latest forecasts for Saturday predict heavy rain and winds gusting in excess of 100km/h to batter the Suzuka Circuit, which lies near the Honshu coast about 300km southwest of the capital.
"Every effort is being made to minimise disruption to the Formula 1 timetable, however, the safety of the fans, competitors and everyone at the Suzuka Circuit remains the top priority," said the FIA.
The qualifying session, originally scheduled to start at 15:00 on Saturday (0800 SA time), determines the starting order for Sunday's race.
It leaves the organisers with two options to form the race grid.
They can either shift qualifying to Sunday morning, something that was done successfully at Suzuka in 2004 and 2010 because of bad weather, or they can use the timings of the drivers from Friday afternoon's second free practice to determine the starting order.
Whatever happens, a postponement of the grand prix to Monday is impossible, the FIA said.
After the tail-end of a typhoon affected the 2014 race at Suzuka, French driver Jules Bianchi crashed heavily after losing control in rain and poor visibility and died the following year from his injuries having never recovered from a coma.
Drivers on Thursday backed changing the weekend timetable.
"I don't think anybody wants to put anybody's life in danger," said Ferrari's four-time world champion Sebastian Vettel.
"The decision is not for us, necessarily, because for us it's nice and easy, cosy, in the garage.
"But for the people out there around the track, it is not nice to be sitting there with rain going sideways."
A blank Saturday would be a huge disappointment to thousands of fanatical supporters at one of the best-attended races on the circuit, but other drivers were prepared for the worst.
"I've got my speedboat on standby, so I'm ready," joked Red Bull's Max Verstappen.
"At the moment it doesn't look very likely. So we'll have a bit more free time on Saturday and it means waking up a little bit earlier on Sunday," he added.
Ferrari's Charles Leclerc said he hoped the FIA would consult the drivers to decide if conditions were safe but thought it "would be pretty clear if we can't drive".