The Ulster Grand Prix road races are "upwards of £250,000 in the red", James Courtney, president of the organising Dundrod and District Club, has said.
The club revealed this week that the future of the event is in "real and imminent danger" because of the scale of financial problems they were facing.
"We've had a few financial issues and the running costs keep going up every year," Courtney told BBC Radio Ulster.
"Sponsorship has been increasing each year but it has just not been enough."
"It has been a struggle to keep things going but we have managed the financial issues quite well.
"Unfortunately this year, with the weather forecast for Saturday being so bad, people just didn't arrive," added the former road race competitor and Ulster Grand Prix winner.
Saturday weather led to financial hit
The extent of the financial crisis affecting the event has led the club to commission an urgent review to assess the viability of running the race meeting in 2020.
A decision will then be taken in the coming weeks as to the future of the club.
"Money we received from Government was spent as of the letter of offer, mainly in safety and paddock improvements. None of the money we received from Government was put towards the general running of the event.
"Our main sources of revenue are entrance fees, car parks, programmes and hospitality. Pre-sales were very good, Thursday sales were very good but on Saturday the people just didn't come.
"When the weather is good and everything is going fine we do get the crowds - it's just on those bad days when people just don't come.
"If we could get ourselves back on an even keel and had some sort of a fall-back fund for any event that is heavily affected by the weather to give us a pull-out on bad days that would be good."
Enniskillen race will not take place in 2020
Meanwhile Irish road racing has suffered another blow with the news that the Enniskillen road races will not take place in 2020.
"After many years of hard work and two successful road race events the club has decided that it is no longer feasible to carry on with the Enniskillen Road Race for 2020," read a statement issued by the club.
"We have worked hard to try and make this event work, but unfortunately due to several reasons, some beyond our control, we now feel that we are unable to run the event next year," they added.