The gods chose Melbourne Cup day to send down the city’s biggest daily rainfall since January, drenching anyone game enough to attend Australian racing’s biggest day.

It was Melbourne’s wettest day since January. Photo: AAP

Melbourne was lashed by heavy rain and even thunderstorms overnight and through the morning, which delivered the city’s biggest daily rainfall in one of the state’s driest years on record.

Bureau of Meteorology senior forecaster Michael Efron said 39 millimetres of rain fell in the Flemington area in the 24 hours to noon, the wettest day in Melbourne city in 10 months.

Racegoers walk in puddles as the rain tumbles down at Flemington. Photo: Getty

Tuesday’s downpour amounted to more than half the November average rainfall of 60 millimetres.

Racegoers take cover as rain tumbles down before race 1. Photo: Getty

Mr Efron told The New Daily that Tuesday’s deluge exceeded more than the September (16.4 millimetres) and October (18.4 millimetres) rainfalls combined.

I’m calling it: ponchos are trending. #MelbourneCup pic.twitter.com/eMByM4F3xY

— Glynis Traill-Nash (@GlynisTN) November 6, 2018

Trains and trams between the city and the racecourse were disrupted by surface flooding, while the runways at Melbourne Airport were closed for 45 minutes, causing flight delays and even a flight diversion to Sydney.

A line of heavy rain and storms has led to 35.0mm being recorded in the #Melbourne city gauge since 9am. This is more than was seen in September and October put together! #MelbourneCup https://t.co/zc3cMk6ClL pic.twitter.com/rjb4AMlYQe

— Bureau of Meteorology, Victoria (@BOM_Vic) November 6, 2018

One racegoer told The New Daily she’s been going to Flemington since 1985 and had never seen anything like it.

“The rain was coming down sideways and the three-storey, multi-million-dollar Lexus marquee sprang several leaks, requiring squads of staff with mops and towels to clean up,” she said.

“Guests in the exclusive marquees sported ponchos, while one smart VRC PR executive wore Hunter gumboots with her pantsuit to welcome international stars Dionne Warwick and Sam Smith to a $790 a head 1 Oliver Lane do.”

The rain didn’t seem to deter early arrivals. Photo: Getty

There was also chaos for Uber passengers, as the main access point too water-logged to be used, leaving thousands of punters to find alternative pick-up points.

Meanwhile, some of the rain-soaked, mud-splattered jockeys in the early races at Flemington seemed almost surprised some races weren’t called off due to the heavy going.

Jockey Noel Callow after Race 1. Photo: Getty

Jockey Beau Mertens said he could see barely two metres in front of himself during his race.

“I have [ridden in conditions like it], and they usually call them off. But I don’t think they’ll be doing that today,” he said.

"I couldn't see much!"@cdsymons chats to Mark Zahra after saluting in the first at @FlemingtonVRC. #7Racing pic.twitter.com/8SttVSrRsm

— 7HorseRacing 🐎 (@7horseracing) November 5, 2018

Anikery went ok considering the conditions. Proud that she did everything right, just wants it a bit further. She’s pulled up really well. When I said I wanted to fill my boots, I had something else on mind! pic.twitter.com/j14RKM7OFs

— Daniel Williams (@danwilliams2038) November 6, 2018

The track was earlier rated a Good 4, but was later downgraded to a Heavy 8.

But as if the racing gods intervened, the showers cleared about noon, with the sun trying hard to break through grey skies from about 1pm.

Mr Efron said the remainder of the day would see a mixture of dry spells and light showers, but they managed to stay away during the main race, only for the skies to open again during the Cup presentation.

The heaviest showers had passed by about noon. Photo: AAP

The weather on #MelbourneCup2018 morning it is sluicing it down @FlemingtonVRC @RacingInsider @godolphin pic.twitter.com/RC7OJ8W76E

— rupert bell (@Rupertbell) November 5, 2018

While the rain may not have been great news for racing fans, it provided some welcome, albeit small, relief for regional Victoria.

Mildura, which had had just 59 millimetres of rain the year to September, had 14.6 millimetres in the 24 hours to 9am on Tuesday, Mr Efron said.

But even with that rain, it is still easily on track be one of the driest years on record for the north-west region of Victoria.