A race record in this year's Sydney to Hobart yacht race appears less likely, while the fleet could encounter gale force winds on Saturday.
The NSW Bureau of Meteorology's manager of weather services, Andrew Treloar said it could well be a wet and humid start to the race on Boxing Day, with temperatures in the mid-20s.
He expects winds to swing to the north east as the fleet make their way down the coast with winds possibly getting up to 20 knots on Thursday evening.
On Friday, the fleet could encounter some frustrating conditions with the possibility of some lighter air while an evening fresh nor'easter is likely to be in play right down the coast, with winds up to 20 knots.
On Saturday morning there may be a freshening north easter and the possibility of a strong wind warning.
"Saturday evening is the crunch time, this is when that big change moves through, at the moment its looking about 10pm," Treloar said..
He said there could be gale force north easters ahead of the front and strong to gale force west to south westers.
"It's going to be a very very tricky race," Wild Oats XI skipper Mark Richards said.
"I don't think the race record, really from what we can see, isn't really (under) threat this year, but you never know.
"Sometimes the fronts come through a little later and the nor'easter could pan out for an extra four, five, six hours and that makes a big difference to these boats."
Perpetual Loyal skipper and owner Anthony Bell, whose boat poses probably the biggest treat to a seventh line honours title for Wild Oats XI, said his mood had changed from depression following the long range forecast, to uncertainty.
"The uncertainty is the big issue coming, it's hard to say who it (the forecast) favours, I think we're in for a proper boat race."