Only half an hour's play was possible in Port Elizabeth, during which six overs were bowled and South Africa moved from their overnight 270 for two to 289 for three.
"It was a very frustrating day," said Du Plessis after play was finally called off more than four-and-a-half hours after the stoppage.
"We had a very good day one and were exactly where we wanted to be."
"ut there?s still quite a lot of time left," he said.
Also Read
"We will just have to do what we plan to do a lot quicker. We?ve got a very good bowling armoury but on the St George's Park wicket it does take a bit longer."
Du Plessis, on 99 overnight, flicked Jerome Taylor's first ball of the day for four runs to raise his century off 229 balls.
The West Indians sought a review and Reiffel was forced to change his decision when 'Snicko' revealed the tiniest of scratches off the bat. It was the first wicket of the series for Taylor.
AB de Villiers joined captain Hashim Amla and hit two handsome drives for four off Jason Holder. He was on nine not out and Amla was unbeaten on 23.
He said the West Indian players had been encouraged by the way they bowled on the first day but wanted to get on the field to make up for the chances they had missed during a 179-run second wicket partnership between Du Plessis and Dean Elgar.