The decision was made by president commissaire Sammy Hardine, on behalf of Cycling South Africa, after consulting his team and the organisers following reports of dangerous riding conditions, particularly on the Du Toitskloof and Bain's passes.
Following a managers' meeting to explain their decision, Hardine said their primary concern in calling off the stage had been the riders' safety.
"This morning was very windy and lots of questions were asked, but after speaking to my panel and the organisers it was decided the stage would go ahead," he said.
"We had hoped that if we could get to the other side of the mountain there would be fair conditions for racing.
"But soon after the 10km neutral zone I was advised by race director Darren Herbst, who was on top of the mountain, that the conditions were extreme."
Hardine said they would monitor the situation before making a call on tomorrow's final stage.
Speaking on behalf of ASG Events, Herbst said it had been a difficult decision to cancel the stage.
He emphasised the point that the riders' safety had been their chief concern.
"It's really windy down here at the start but times that by 10 and that's what you are getting on the passes."
Bestmed sales and marketing chief Chris Luyt, who is riding in the race, said he felt the right decision had been made.
"It is disappointing, but you can't control nature and I support the commissaires' call," he said.
"We also want to use the opportunity to ask the motorists to have patience with the riders during the race, which is bringing in between R20m and R30m of revenue to the region."
The cancellation of the stage means South Africa's premier road classic, presented by the City of Drakenstein and Scicon, will be decided over four stages.
Luyt wished everyone luck for tomorrow's final day, which will see the riders finish at the Taal Monument above Paarl after a relatively short 86.7km stage.
Pro Touch's Myles van Musschenbroek and dormakaba's Candice Lill will begin the final day in yellow.
Caption: A marshal on the Bestmed Tour of Good Hope informs the riders that the fourth stage has been cancelled due to heavy winds shortly after the start from La Paris Estate near Paarl today. Photo: Robert Ward