Powell could give new clues about the timing and pace of policy normalisation by the U.S. central bank.
At 1420 GMT, the rand traded at 15.6425 against the dollar, around 0.2% stronger than its previous close. The dollar was little changed against a basket of currencies.
The rand has tended to track global factors in recent sessions and is highly sensitive to shifts in the outlook for U.S. monetary policy.
In a light week for domestic economic data, Statistics South Africa figures on Tuesday showed November manufacturing output fell 0.7% year-on-year, following a revised 8.5% slump in October when a major metalworkers' union was on strike.
Stocks rose marginally as investors built up positions ahead of Powell's testimony, with the benchmark all-share index closing up 0.15% at 73,943 points. The blue-chip index of top 40 companies closed 0.22% higher at 67,260 points.
The government's benchmark 2030 bond was slightly weaker, with the yield rising 6.5 basis points to 9.550%.
(Reporting by Alexander Winning; Editing by Devika Syamnath)
