At 1515 GMT, the rand traded at 18.5450 against the dollar, about 0.4% weaker than its previous close. Earlier in the day the rand was down 1%.
The dollar was last down about 0.06% against a basket of other global currencies.
Powell is due to speak at 1900 GMT, with markets focused on whether he will push back against expectations that the U.S. central bank is done hiking rates.
"The ZAR bulls may regain some momentum if there are any dovish signals from the Fed Chair, which would reinforce expectations that the Fed is done hiking and could look to cut rates through the latter half of 2024," said Bheki Mahlobo, a market analyst at ETM Analytics.
Like other risk-sensitive currencies, the rand often takes direction from global drivers such as U.S. monetary policy.
Locally, South Africa's mining output fell 1.9% year on year in September while manufacturing output fell 4.3%, Statistics South Africa data showed on Thursday.
On the Johannesburg Stock Exchange, the blue-chip Top-40 index closed 0.3% lower.
South Africa's benchmark 2030 government bond was weaker, with the yield up 2.5 basis points to 10.340%.
(Reporting by Tannur Anders, Editing by Nellie Peyton, Kirsten Donovan)
