Balls were being blown around the greens, leading tournament officials to suspend play for about three hours.
That caused a backup that left most of the field on the course when play was halted due to darkness. Those players are to complete the first round Friday before second-round play.
Val Zyl got in most of his round before the suspension and ended up at 6-under-par 66. Adilson Da Silva had five birdies in his first six holes Thursday but only completed two more before play was called. He's in second place, one stroke back of Van Zyl.
John Parry was at 4-under 68 and alone in third. Oliver Bekker shot 69 and is tied at 3-under with Mikko Korhonen, who got in 11 holes Thursday, and Andrew Curlewis, who finished eight.
Van Zyl, starting on the back nine of the East London Golf Club, had birdies at Nos. 11 and 14 before an eagle at the 534-year, par-5 15th pulled him in to the lead. He birdied the first hole but had a bogey at No. 2 before play was suspended.
He had birdies on his first two holes after the break, dropping 2-foot birdies putts after driving both the short par-4 fifth and sixth holes.