At 1627 GMT, the rand traded at 16.8100 against the dollar, 0.16% stronger than its previous close.
"Should the Fed deliver a 100 bp hike this week, the rand will likely weaken, while a smaller move (50 bp) could see rand strengthen," Investec economist Annabel Bishop said in a research note, adding the most likely outcome was, however, the 75 basis point (bp) increase that markets anticipate.
South Africa's central bank raised its main lending rate last week, by 75 bps to 5.50%.
On the stock market, the Top-40 and the broader all-share indexes both dipped around 0.5%.
Shares in Anglo American Platinum closed down 2.18% after the miner reported a 43% drop in half-year profit due to weaker metal prices and lower production compared with record sales a year ago.
"Lower platinum, palladium and rhodium prices combined with a rising cost base are going to make it a difficult second half, though better weather should enable production to recover," SP Angel analysts said in a note.
President Cyril Ramaphosa is set to address the nation later in the evening on the government's plans to tackle the country's worst-ever power crisis.
State utility Eskom has been implementing regular scheduled electricity cuts since late June that have prompted public anger and hampered businesses.
The government's benchmark 2030 bond was almost unchanged, with the yield at 10.520%.
(Reporting by Bhargav Acharya in Bengaluru and Anait Miridzhanian in GdanskEditing by Robert Birsel and Mark Potter)
