It comes from the expression "cold enough to freeze the balls off a brass monkey" and organisers were settling into the first hoar frost at the rally in years — maybe ever.
The rally starts today and finishes tomorrow but organisers spent Thursday and Friday setting up camp.It is held at the Idaburn Dam, near Oturehua, every year.
Brass Monkey chairman Phil Scorringe said this was the 38th annual rally and possibly the first hoar frost.
"We had a guy who’s been coming for 31 years and he said he hasn’t seen anything like this," Mr Scorringe said.
Yesterday morning, the temperature on site was -12degC, the coldest in the last few years.
Mr Scorringe said last year the lowest temperature was 4degC, comfortably above freezing level.But even though it was "super cold", Mr Scorringe was not complaining.
"It’s just gorgeous."
Mr Scorringe expected the rally to attract 1300 bikers from all around New Zealand. He described it as a "party and a chance to catch up with mates," with bonfires, fireworks and bands.
