Punters huddling up under patchy skies at Flemington

The umbrellas and ponchos have come out as patchy weather descends on Flemington ahead of the Melbourne Cup.

The Bureau of Meteorology has forecast "one and off" showers for the afternoon, with an even chance rain could fall during the premier event.

Video and snapshots taken at the racecourse show punters doing their best to save their frocks and suits as the sky started to spit.

But experts say the track will hold at this point, even in event of a heavy downfall, while the BOM says the drizzle shouldn't put too much of a damper on the day.

"It's actually going to be the same temperature — 18 degrees — as the race last year,"meteorologist Tony Bannister told the ABC.

"We're not forecasting a lot of rain but probably just enough to be annoying, and if you are a betting person there's probably still a 50/50 chance of showers during the big race itself.

"We're looking like there's going to be a weak front move through southern Victoria during the day and showers in the metro area will develop late morning, early afternoon."

It's also possible the Cup could be run during a spell of sunshine.

Today’s showers will be slightly heavier than those that fell yesterday, with up to three millimeters forecast for Melbourne.

It will be windy at the races "but not enough to blow hats away and ruin hairdos or anything like that", Mr King said.

The BOM says the winds will be northwesterly at 20 to 30km/h before turning west to southwesterly during the afternoon.