The cloud was spotted about 5.30pm on Thursday over Omakau after a brief shower of hail and a thunderclap drew people’s attention to the sky.
Central Otago Trotting Club president Graham Sinnamon said it was an unexpected addition to the annual Omakau trots.
"It was more spectacular than threatening ... We simply don’t see stuff like that very often," Mr Sinnamon said.
"I’d like to think it was just a part of the entertainment that Omakau put on as part of the big day. "
Race 10, the Gallagher Family Gold Cup Mobile Trot, was briefly delayed as a precaution.
The race was named in honour of the Gallagher family’s long association with the trotting club — the cup was usually presented by Paul Gallagher.
However, Mr Gallagher died last year and Thursday’s race was the first since his death, Mr Sinnamon said.
"Because it happened at the race where we were honouring him, there was a school of thought that it was just Paul Gallagher running around up there ... making sure that everybody still remembered that he was there.
The weather did not detract from a great day of racing, Mr Sinnamon said.
Omakau resident Adam Rubie said he and his wife watched the funnel cloud, which was visible for about 10 minutes.
"We were lying in the backyard enjoying the sunshine until . . . the clouds suddenly started to grow."
Over 20 minutes, the sky was filled with thunderclouds and the funnel cloud formed.
Summer storms were common in the area but funnel clouds were not, he said.
"I guess weather in general around the world is just becoming a little more playful than it has been in the past."
MetService meteorologist Surprise Mhlongo said funnel clouds were often embedded in thunderstorms and could not be predicted.
"The conditions [on Thursday] looked favourable," he said.
