Gumboots may be the footwear of choice at the "Party in the Puddle" at the Wingatui races today, organisers say.
Otago Racing Club marketing manager Megan Brick said heaters and extra flooring had been ordered to combat the cold and wet conditions.
Racegoers should still dress smartly with fascinators and bow-ties but flat shoes were advised for the heavy conditions underfoot, she said.
About 8000 racegoers were expected, she said.
Otago Racing Club chief executive Andre Klein said gumboots would be suitable footwear.
Some of the marquees had been renamed to suit the soggy conditions, he said.
The Party-in-the-Paddock was now the Party-in-the-Puddle and the Fashions on the Field was Flash Flood in the Field, he said.
Arthur Barnett cosmetic buyer Lorna Meddings said she would judge Fashions on the Field, with radio DJ Alison Leonard and world champion cyclist Alison Shanks.
Entrants would not win wearing gumboots, Ms Meddings said.
"Regardless of the weather, we will be looking for well-presented, confident contestants.
"Gumboots will ensure that you don't make the final 10," she said
MetService forecaster Philippa Murdoch said the frost forecast for this morning could make for a "fairly chilly" raceday and, although there was a chance of early morning showers, the day would warm up and temperatures would reach about 14degC, she said.
