At 0636 GMT, the rand was trading at 16.0050 against the dollar, 0.53% lower than its previous close.
The Dollar Index, which tracks the greenback against six other major currencies, was up 0.34% to 104.79.
Powell is due to begin testimony before Congress on Wednesday, with investors looking for further clues about the possibility of another 75 basis point rate hike in July.
At around 0800 GMT, Statistics South Africa is due to release May Consumer Price Index figures.
Analysts polled by Reuters expect annual consumer price inflation to pick up to 6.2% from 5.9% in April, above the upper limit of the central bank’s target range from 3% to 6%.
The government’s 2030 benchmark bond remained stable at 10.160%.